Next Article in Journal
What Is the Exact Contribution of PITX1 and TBX4 Genes in Clubfoot Development? An Italian Study
Next Article in Special Issue
Molecular Characterization of Tinospora cordifolia (Willd.) Miers Using Novel g-SSR Markers and Their Comparison with EST-SSR and SCoT Markers for Genetic Diversity Study
Previous Article in Journal
Functional Study on Cytochrome P450 in Response to L(−)-Carvone Stress in Bursaphelenchus xylophilus
Previous Article in Special Issue
Systematic Identification and Validation of Suitable Reference Genes for the Normalization of Gene Expression in Prunella vulgaris under Different Organs and Spike Development Stages
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Genes
Volume 13
Issue 11
10.3390/genes13111957
genes-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Glucomannan in Dendrobium catenatum: Bioactivities, Biosynthesis and Perspective

by
Luyan Qi
1,†,
Yan Shi
1,†,
Cong Li
1,2,
Jingjing Liu
1,2,
Sun-Li Chong
1,
Kean-Jin Lim
1,
Jinping Si
1,2,
Zhigang Han
2,* and
Donghong Chen
1,*
1
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Hangzhou 311300, China
2
National Innovation Alliance of Dendrobium catenatum Industry, Engineering Technology Research Center of Dendrobium catenatum of National Forestry and Grassland Administration, Hangzhou 311300, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Genes 2022, 13(11), 1957; https://doi.org/10.3390/genes13111957
Submission received: 17 September 2022 / Revised: 23 October 2022 / Accepted: 24 October 2022 / Published: 27 October 2022
(This article belongs to the Special Issue Phylogenetics, Genetics, and Breeding of Medicinal Plants)
Browse Figures
Review Reports Versions Notes

Abstract

:
Dendrobium catenatum is a classical and precious dual-use plant for both medicine and food in China. It was first recorded in Shen Nong’s Herbal Classic, and has the traditional functions of nourishing yin, antipyresis, tonifying the stomach, and promoting fluid production. The stem is its medicinal part and is rich in active polysaccharide glucomannan. As an excellent dietary fiber, glucomannan has been experimentally confirmed to be involved in anti-cancer, enhancing immunity, lowering blood sugar and blood lipids, etc. Here, the status quo of the D. catenatum industry, the structure, bioactivities, biosynthesis pathway and key genes of glucomannan are systematically described to provide a crucial foundation and theoretical basis for understanding the value of D. catenatum and the potential application of glucomannan in crop biofortification.

Graphical Abstract

1. Introduction

Dendrobium catenatum (also named D. officinale) is a rare and precious Traditional Chinese Medicinal (TCM) plant, and it was first recorded in the earliest works of Chinese Medicine, Shen Nong’s Herbal Classic, written in the Eastern Han Dynasty nearly 2300 years ago. The main medicinal part of D. catenatum is the stem, which has the effects of nourishing yin, antipyresis, tonifying the stomach, and promoting fluid [1]. Wild D. catenatum is on the verge of extinction, and it was listed as a third-class protected species in the Regulations on the Protection and Management of Wild Medicinal Resources issued by the State Council of China in 1987 and as an endangered plant by the China Plant Red Data Book in 1992. Subsequently, D. catenatum was listed as critically endangered on the International Union for Conservation of Nature (IUCN) Red list (Critically Endangered A4c ver 3.1), and as a second-class national protected endangered plant on the List of Rare and Endangered Plants of the People’s Republic of China in 2009 [2]. In the 2010 edition of the Pharmacopoeia of the People’s Republic of China, D. catenatum (D. officinale) was separated from the “Dendrobium” item to form a single item. In 2018, D. catenatum was listed as the top one of the new “Zhe-Ba-Wei” Chinese Medicinal Materials by Zhejiang province. In 2019, D. catenatum was included in the catalogue of pilot work of food and drug material management by the National Health Commission of the People’s Republic of China, which indicates that D. catenatum is officially recognized as an edible material. In 2021, as a second-level protected plant, D. catenatum was further included in the new version of the List of National Key Protected Wild Plants jointly issued by the National Forestry and Grassland Administration and the Ministry of Agriculture and Rural Affairs of the People’s Republic of China.
As a traditional dual-purpose plant for both food and medicine, D. catenatum research and industry have experienced three developmental stages (I~III). (I) The initiation stage. Since the 1970s, preliminary studies on the improvement of both seedling propagation and artificial cultivation technologies have been carried out. D. catenatum raw materials were obtained from wild resources by unrecoverable over-exploitation. (II) The blooming stage. In the beginning of the 2000s, with breakthroughs in key technologies for seed production, tissue culture, and planting substrates of D. catenatum, the artificial-sheltered cultivation mode (Figure 1A) with high yield was dramatically developed, resulting in a sharp rise of a ten-billion-level industry [3]. (III) The plateau stage. From the 2020s onward, simulated wild cultivation mode with D. catenatum directly planted on the rock and trunk (Figure 1B,C) is popular due to its high TCM quality, contributing to breaking through the bottleneck and further transformation and upgradation of the D. catenatum industry. Therefore, D. catenatum has progressed from its natural wild state (endangered) to facility cultivation (high-yield), then to imitation wild cultivation (high-quality), leading to species conservation and industrial rise with combined ecological and economic benefits.
Modern studies have shown that the main active components of D. catenatum are polysaccharides, alkaloids, phenols, terpenes, and flavonoids [4]. Among them, polysaccharide is closely related to its pharmacological activity and is an important index for the evaluation of D. catenatum’s quality. The main active polysaccharide in D. catenatum stem is glucomannan, which has antioxidant and mild immunostimulatory activity to protect macrophages from hydrogen peroxide (H2O2)-induced oxidative damage [5]. Glucomannan, as an excellent soluble dietary fiber, has the virtues of regulating the intestines and stomach, improving immunity, lowering blood sugar and blood fat, fighting cancer, and losing weight [6,7]. In addition, mannose as the main glucomannan component has been identified to inhibit cancer cell growth by interfering with cellular glucose metabolism [8].
Hidden hunger refers to malnutrition due to nutritional imbalance in the human body, even having taken in enough energy. More than two billion people worldwide have suffered from hidden hunger, which is highly correlated with the status that three staple cereals (rice, maize, and wheat) provide 60% of the world’s food intake [9]. Recently, rediscovery and utilization of a nutrient-rich variety of “forgotten crops” in Asia offers a viable and promising approach to eliminate hidden hunger [10]. Glucomannan belongs to soluble hemicellulose and is an excellent source of soluble dietary fiber as the seventh essential nutrient in the human body. Therefore, incorporating D. catenatum as a rich source of glucomannan into the daily diet contributes to promoting nutritional diversification and alleviating hidden hunger.

2. Feature and Structure of Glucomannan

Unlike other soluble fibers, glucomannan is characterized by high viscosity [11]. As a hemicellulose polysaccharide, glucomannan is ubiquitous in the plant cell wall. Moreover, glucomannan exists as energy storage substance in Araceae, Liliaceae, and Iridaceae and Orchidaceae [12]. It was reported that glucomannan contributes to plant tolerance to the lack of water as a compatible solute and the succulence in Aloe vera [13]. Storage glucomannans in distinct species display different structures. The mannose:glucose (Man:Glc)ratio is 1.6:1.0 in glucomannan from Amorphophallus konjac and 3.0:1.0 in glucomannan from Orchis mascula [14,15]. The Man:Glc ratios of three glucomannans (ASP-4N, ASP-6N and ASP-8N) in Aloe leaves are 19.13:1, 8.97:1, and 2.96:1, respectively [16]. In addition, glucomannan can also be obtained from microorganisms, such as the cell walls of bacteria, yeast, or fungus [17,18]. Natural glucomannan is composed of D-glucose and D-mannose linked by a β-1,4-glucopyranoside bond to form polymer heteropolysaccharides in a certain molar ratio [19]. Moreover, the C3 position of D-mannose on the main chain can be linked to polysaccharides in the form of β-1,3-glycosidic bond or β-1,6-glycosidic bond [20].
Glucomannan is the main polysaccharide active component in D. catenatum (Figure 2, Table 1), and its derivatives also contain other monosaccharides, such as galacturonic acid, glucuronic acid, and galactose [21]. The contents of mannose and glucose in total polysaccharides from D. catenatum are 120.60 mg·g−1 and 71.23 mg·g−1, respectively [22]. Several glucomannans from D. catenatum have been reported to exhibit different Man:Glc molar ratios [5,23,24], and contain abundant O-acetyl groups [25,26,27]. Acetylation can increase the activity and health benefits of glucomannan [28].

3. Applications of Glucomannan

3.1. Medical Applications

D. catenatum has multiple traditional functions and has been developed into various medicines, such as Mailuoning injection (Jinling Pharmaceutical Co., Nanjing, China), Tongsaimai tablet (Jiangsu Kangyuan Sunshine Pharmaceutical Co., Nanjing, China), and Dendrobium nightlight pill (Tong Ren Tang, Beijing, China). Modern medicine has shown that D. catenatum polysaccharides have diverse bioactivities, including immunomodulatory, anti-tumor, gastro-protective, hypoglycemic, anti-inflammatory, hepatoprotective, and vasodilating effects [37]. In this review, major emphasis will be placed on the gastrointestinal protection, immunomodulatory, anti-cancer, hypoglycemic, and hypolipidemic functions of D. catenatum glucomannan (Figure 3).

3.1.1. Intestinal Health Improvement

It has been reported that glucomannan can modulate mouse cecal and fecal microbiota with favorable prebiotic effects [38]. The unique properties of glucomannan hydrolysate make it valuable as a prebiotic in a wide range of food, feed, and pharmaceutical products [39]. Prebiotics promote specific changes in the gastrointestinal microbiota [40], promote the growth of probiotics such as Lactobacillus and Bifidobacterium, inhibit the proliferation of harmful bacteria, reduce inflammation, improve the integrity of the intestinal mucosa, promote nutrient absorption [41], and control the blood glucose level of patients with type 2 diabetes [42]. Glucomannan selectively stimulates the production of beneficial gut microflora such as probiotics and benefits the treatment of functional gastrointestinal disorders related to abdominal pain in mice [43,44,45]. The combined laxative of glucomannan-probiotic promotes defecation in constipated rats [46]. Mannose-oligosaccharides, the oxidative degradation product of glucomannan, are potential prebiotics, which can affect the growth and species abundance of fecal microbiota and regulate the balance of intestinal flora [47,48]. For instance, D. catenatum polysaccharide DOP can restore the diversity of intestinal flora and regulate the abundance of intestinal flora by inhibiting the overexpression of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β), restoring the level of short-chain fatty acids (SCFAs), activating G-protein-coupled receptors (GPRs), and regulating the intestinal flora to alleviate the symptoms of colitis in mice [49].
Glucomannan also plays a direct role in protecting the intestinal epithelium. D. catenatum polysaccharide DOP is not easily digested and absorbed in the human body but is degraded into SCFAs by the gut microbiota in the large intestine, therefore improving intestinal health [22,50]. In addition, D. catenatum glucomannan can reduce intestinal epithelial injury and regulate intestinal mucosal immunity by keeping a balanced ratio of pro- and anti-inflammatory cytokines and regulating the expressions of toll-like receptors (i.e., TLR-2, TLR-4, TLR-6, and TLR-9) important for recognizing pathogen-associated molecular patterns derived from various microbes in mice [51].

3.1.2. Immunomodulatory Activity

Glucomannan, one of the natural bioactive ingredients, can be used as an ideal immunomodulatory agent. Glucomannan can reduce brain inflammation, improve hippocampal neuron damage, maintain hippocampal cognitive function, and play an anti-epileptic role in epileptic rats [52]. D. catenatum polysaccharide DOPW3-B can improve the intestinal mucosal immune activity by increasing at Peyer’s patches the levels of interferon-γ (IFN-γ) and interleukin-4 (IL-4), two key effector cytokines for the differentiation of T helper types 1 and 2 with a positive effect on mesenteric lymph nodes [31,53]. Glucomannan can increase the expression of several cytokines that are important for immune homeostasis (e.g., TNF-α, IL-β and IL-10) [54]. Meanwhile, glucomannan plays a pivotal role in regulating the activation and proliferation of macrophages [55], and promoting phagocytosis [29]. Finally, the pretreatment of D. officinale with organic solvents enhances the immunostimulatory activity of polysaccharides and affects the mannose/glucose ratio of polysaccharides, which plays an important role in immunostimulation [56].

3.1.3. Anti-Cancer Activity

In a zebrafish xenograft model, D. catenatum polysaccharide DopW-1 inhibits the proliferation of HT-29 cells by the apoptosis pathway and has an anti-tumor effect on colorectal cancer [57]. It is known that hyper-activation of the phosphatidylinositol 3 kinase/protein kinase B (PI3K/AKT) signaling pathway in human cancers can promote the proliferation and survival of tumor cells [58]. Glucomannan can block the PI3K/AKT pathway, thereby promoting the apoptotic rate and reducing the proliferation ability of tumor cells [59]. In parallel, glucomannan can also inhibit the expression of major chemokine receptors, chemokine receptor 4 (CXCR4) and CC chemokine receptor 7 (CCR7), found in a wide range of tumor cells, thus reducing the dissemination ability of tumor cells [60]. In addition to directly interfering with tumor cells, glucomannan also acts in an indirect manner. The D. catenatum polysaccharide DOPa-3 significantly inhibits the formation and growth of colon tumors and alleviates colon injuries [61]. In rats, DOPA-4 effectively inhibits precancerous lesions of gastric cancer induced by 150μg/mL MNNG [62]. D. catenatum polysaccharides can reduce oxidative stress level, inhibit stress-induced activation of adenosine monophosphate-activated protein kinase (AMPK)/UNC-51 like autophagy activating kinase 1 (ULK1) pathway and the expression of light chain 3 (LC3) I and LC3 II proteins, reduce Beclin1 expression, and then reduce hypoxia/reoxygenation induced astrocyte autophagy, reduce human astrocyte apoptosis, and promote astrocyte survival [63].

3.1.4. Hypoglycemic Activity

Glucomannan is suitable as a dietary fiber supplement for the treatment of being overweight, hyperlipidemia, and diabetes. D. catenatum glucomannan DOP can alleviate hyperglycemia in high fat diet (HFD)/streptozocin (STZ)-induced diabetic mice through promoting the synthesis of liver glycogen and inhibiting the degradation of liver glycogen [64].
DOP treatment can reduce the level of bile acid in diabetic rats, reduce the binding of bile acid to the nuclear receptor FXR or the membrane receptor TGR5, increase the level of glucagon-like peptide-1 (GLP-1), and improve glucose and lipid metabolism and insulin sensitivity [65]. DOP promotes glycogen synthesis by regulating the expression of glycogen synthase kinase 3β (GSK-3β) and glycogen synthase (GS) in the liver or glucose transporter 4 (GLUT4) in muscle. Glucose levels are reduced by regulating the activity of glucose metabolism enzymes in the liver, including pyruvate kinase (PK), hexokinase (HK), and phosphoenolpyruvate carboxykinase (PEPCK) [66]. On the other hand, DOP can delay diabetic cataract by decreasing the level of serum malondialdehyde (MDA), increasing the activity of superoxide dismutase (SOD) and enhancing its antioxidant capacity [49]. Glucomannan AABP-2B, isolated and purified from Anemarrhena asphodeloides, demonstrates its hypoglycemic effect by inhibiting α-glucosidase activity and activating irS-1/PI3K/Akt signaling pathway in insulin-resistant cells [67]. Effects of glucomannan on insulin sensitivity contribute to weight loss, and taking as little as 4 g of glucomannan per day can promote weight loss [68].

3.2. Daily Application

3.2.1. Cosmetics

D. catenatum extracts are used as cosmetic raw materials to effectively solve the skin problems caused by yin deficiency and fire hyperactivity due to their rich polysaccharides, flavonoids, and other nutrients that are absorbed through the skin and have good moisturizing, anti-aging, and anti-wrinkle effects [69]. The aqueous extract of D. catenatum can resist drying damage to epidermal cells, increase cell vitality, and improve skin moisture content [70]. D. catenatum polysaccharide DSP has strong antioxidant activity, can scavenge DPPH free radicals, and has a better inhibitory effect on lipid peroxidation and oxidative damage of red blood cells [71,72]. Macromolecular polysaccharide as the main moisturizing component in D. catenatum is a kind of polyhydroxyl polymer, whose polar groups can form hydrogen bonds with water molecules to bind water. Meanwhile, polysaccharide can form a uniform film on the skin surface to prevent water loss [73]. Dendrobium huoshanense polysaccharide has certain hygroscopic and moisturizing properties with a higher moisture retention rate than glycerin, is non-irritating to skin, and serves as a natural moisturizing agent [74]. So far, many related skin care products are popular in the market, such as moistening and skin brightening masks with D. catenatum (SENYU, Jinhua, China), Dendrobium emulsion (MISS QUEEN, Ningbo, China), and D. catenatum skin corset firming lotion (BOTANIERA, Hangzhou, China).

3.2.2. Food and Functional Food

Glucomannan has wide application prospects in the food industry and can be used as a food additive, meal substitute food, and health care products, such as Tiepifengdou capsules, oral liquid, decoction pieces, yogurt [75], teabags [76,77], beverages, and noodles [78], and has been applied to a number of patents [79]. Due to its large molecular weight and strong water binding ability, glucomannan has excellent hydrophilicity, gelation, emulsification, film formation, thickening, and other unique functional properties [80]. With alkali treatment, the acetyl group in glucomannan is removed to promote the formation of intramolecular and intermolecular hydrogen bonds and get a gel with excellent stability [81]. Glucomannan is a licensed food additive, which is used as a stabilizing, thickening, and gellating agent [82]. For example, in yogurt and other drinks, glucomannan can be used as a thickening agent to increase flavor and nutrition [82]. In sausages, hams, and other meat products, glucomannan can replace fat, reduce fat content, increase viscosity, and water retention, to improve the texture and flavor of meat [83]. In starch products, the addition of glucomannan affects the paste characteristics, rheological properties, and texture of the starch system [84]. In addition, glucomannan can be used for food preservation, such as glucomannan film, which has good stability and food applicability and can be used for fruit and vegetable coating preservation and flavor microcapsule production [85].

4. Glucomannan Biosynthesis Pathway in Plant

In the biosynthesis pathway of glucomannan (Figure 4), the photosynthates of leaves are transported to the D. catenatum stem in the form of sucrose, which is then decomposed into glucose (Glc), UDP glucose (UDP-Glc), and fructose (Fru) under the action of sucrose synthase (SUS) and invertase (INV), and then, under the action of hexokinase (HXK) and fructokinase (FRK), Glc-6-P is further catalyzed by phosphoglucomutase (PGM) to produce glucose-1-phosphate (Glc-1-P). At the same time, Fru-6-P is catalyzed by phosphate mannose isomerase (PMI) to produce mannose-6-phosphate (Man-6-P), which is converted to mannose-1-phosphate (Man-1-P) by phosphomannomutase (PMM). GDP mannose pyrophosphorylase (GMP) catalyzes the production of GDP mannose (GDP-Man). Glc-1-P is converted to GDP-glucose (GDP-Glc) by GDP-Glc pyrophosphorylase (GGP) and Glc-1-P is also converted to ADP-glucose (ADP-Glc) by ADP-Glc pyrophosphorylase (AGP). Subsequently, GDP-Man, GDP-Glu, or ADP-Glu are each transported into the Golgi apparatus by specific transporters, and they are used as substrates of cellulose-like synthases A/D (CSLA/D) to synthesize glucomannan. Additionally, GDP-Man is also used for the synthesis of vitamin C/ascorbic acid (AsA) [86]. Glucomannan synthesized in the Golgi matrix might have two roles. On the one hand, it is localized in the cell wall through vesicle transport and functions as a structural polysaccharide [87]. On the other hand, glucomannan also acts as a storage polysaccharide in some plants, such as D. catenatum, Konjac, and A. vera. In Konjac, glucomannan was discovered to accumulate in the egg-shaped idioblast within the parenchyma [12].

5. Research Progresses of Key Glucomannan Biosynthetic Genes in Plant

The pathway of glucomannan synthesis involves some specific key enzymes: phosphate mannose isomerase (PMI), phosphomannomutase (PMM), GDP-mannose pyrophosphorylase (GMP), and cellulose-like synthase A/D (CSLA/D). PMI, PMM, and GMP can provide precursors for the synthesis of GDP-Man, which serves as not only the glycosyl donor and metabolic intermediate widely existing in various organisms but also the substrate of the biosynthesis of glucomannan and ascorbic acid (AsA) [86]. In D. catenatum, the expression levels of DcPMI, DcPMM, DcGMP2, and DcCSLA4/8/13 in the stem are significantly higher than those in other tissues (Figure 5), indicating their important roles for glucomannan accumulation in the D. catenatum stem.

5.1. Phosphate Mannose Isomerase (PMI): Fru-6-P ↔ Man-6-P

Phosphate mannose isomerase (PMI) catalyzes the reversible conversion between Fru-6-P to Man-6-P in eukaryotes and prokaryotes and is a key enzyme during GDP-Man production [90], required for the first step of the mannose/L-galactose pathway during AsA biosynthesis in plants [91]. In Arabidopsis, there are two PMI1 isozymes, but PMI1, rather than PMI2, is involved in AsA biosynthesis. PMI1 has constitutive expression in both vegetative and reproductive organs under normal growth conditions, whereas PMI2 has no expression in any organs under light. Continuous light can induce PMI1 expression and an increased AsA level in leaves, whereas long-term darkness can induce PMI2 expression and decrease the AsA level. The diurnal expression pattern of PMI1 is in parallel with the total PMI activity and the AsA content in leaves. Moreover, knockdown of PMI1 results in a substantial decrease in the total AsA content of leaves, whereas knockout of PMI2 does not affect the total AsA levels in leaves [92]. In addition, AsA plays an essential role in scavenging reactive oxygen species (ROS) produced during cell metabolism and stress, and increase in the AsA level contributes to an improvement in abiotic stress tolerance [93]. Overexpression of BcPMI2 from non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) improves AsA content and tolerance to oxidative and salt stress under NaCl or H2O2 treatment, although transgenic tobacco has lower contents of AsA and soluble sugar than WT under normal conditions [94].
To date, PMI-like genes are mainly used in the mannose selection-based plant transformation system (plant PMI/Man system), which is non-antibiotic and environmentally friendly [95]. Most plant cells are sensitive to mannose and fail to utilize mannose as a sole carbon source because mannose can be taken up and phosphorylated to Man-6-P by endogenous hexokinase, but Man-6-P is not further utilized in the absence of enough PMI activity, subsequently leading to the accumulation of Man-6-P, inhibition of phosphoglucose isomerase, glycolysis blocking, and cell growth arrest [96]. However, plant cells with high PMI activity through genetic modification can metabolize Man-6-P and enter into glycolysis for ATP production and normal growth [97]. As a new safe positive selectable marker gene, PMI has been successfully used in the genetic selection of many plants, such as rice, maize, wheat, sorghum, sugarcane, onion, tomato, potato, cassava, grape, apple, cucumber, sugar beet, papaya, Arabidopsis, cabbage, and so on [98,99,100]. The Escherichia coli PMI (EcPMI) gene was first used in the plant PMI/Man system, which is the most popular one [101]. In 2009, the first genetically modified maize MIR604 via the EcPMI/Man selection system was approved for food and feed use, import, and processing in the European Union (European Food Safety Authority, 2009). Saccharomyces cerevisiae PMI (ScPMI) can also be used as a selectable marker in rice transformation [98]. However, non-plant type PMIs can still raise public safety concerns, and plant type PMIs may offer a superior alternative [102]. Hu et al. first proved that plant PMI genes from Chlorella variabilis and Oryza sativa can also be used as selectable markers to obtain transgenic plants exhibiting an accumulation of PMI transcripts and enhancement of PMI activity [100]. Through the selection system based on the green microalga Chlorococcum sp. PMI (ChlPMI), a polycistronic gene cluster containing crtB, HpBHY, CrBKT, and SlLCYB is transformed into tomato, resulting in the production of high astaxanthin content [103].

5.2. Phosphomannomutase (PMM): Man-6-P ↔ Man-1-P

Phosphomannomutase (PMM) catalyzes the interconversion between Man-6-P and Man-1-P and provides precursors for the synthesis of GDP-Man. GDP-Man is not only used for the synthesis of glucomannan but is also an indispensable intermediate in the AsA biosynthesis pathway. The PMM enzyme isolated from the cinnamon seed has the activity of converting D-glucose produced by photosynthesis or glycolysis into a mannose component of plant storage polysaccharide [104]. At present, there is much research on the catalytic role of PMM in the AsA synthesis pathway. In tobacco, decreased expression of PMM via the VIGS technique resulted in a reduction of AsA content in leaves, while overexpression of PMM increases AsA content in leaves [105]. Transgenic tobacco plants overexpressing the acerola (Malpighia glabra) PMM gene show around a 2-fold increase in AsA content compared with WT, which correlates with the level of PMM transcripts and the corresponding enzymatic activities [106]. Overexpression of rice PMM in transgenic rice increased AsA content in seeds by 25–50% [107]. Overexpressing D. catenatum PMM gene in Arabidopsis, resulting in a significant increase in the contents of both AsA and polysaccharide [108].

5.3. GDP-Mannose Pyrophosphorylase (GMP): Man-1-P ↔ GDP-Man

GDP-mannose pyrophosphorylase (GMP) (also named Vitamin C Defective1, VTC1) catalyzes the conversion of Man-1-P and GTP to GDP-Man and pyrophosphate. GMP plays an important role in maintaining the AsA level and redox balance in plants. Compared with WT, the Arabidopsis vtc1-1 mutant accumulated only 25% of leaf AsA content, but had no effect on the AsA redox state [109]. Arabidopsis KONJAC1 (KJC1) and KJC2 interact with VTC1 to stimulate GMP activity to affect the accumulation of AsA and glucomannan, and VTC1 mutants cause severe dwarfism [110]. The acerola plant has very high AsA levels, consistent with that of the M. glabra MgGMP gene promoter, which has higher activity than 35S and Arabidopsis GMP promoters. Transgenic tobacco plants containing the MgGMP gene and its original promoter, which displayed about 2-fold increased levels of AsA [111]. Transgenic tomatoes overexpressing a yeast-derived GMP exhibit up to a 31 and 17-fold increase in GMP activity in leaves and green fruit, respectively. The AsA levels increase by up to 70% in leaves, 50% in green fruit, and 35% in red fruit, especially in photosynthesizing organs [112]. The overexpression of tomato SlGMP3 increases total AsA levels and tolerance to oxidative stress in tomatoes and high or low temperature stress in tobacco, whereas knockdown of SlGMP3 in tomatoes leads to substantially decreased AsA content and a defective phenotype with lesions and senescence due to failing to instantly detoxify ROS [113,114]. Overexpression of tomato GMP in potatoes can improve the content of AsA and dehydroascorbate (DHA) under low temperature stress and enhance the cold tolerance of potatoes [115]. Transgenic tobacco expressing Pogonatherum paniceum GMP has a high germination rate and high AsA content under drought and salt stress, and has strong salt tolerance and drought resistance [116]. Overexpression of D. catenatum GMP in Arabidopsis results in increased mannose content in water-soluble polysaccharides and enhances salt stress tolerance [117], consistent with salt hypersensitivity in the Arabidopsis vtc-1 mutant [118].
In addition, the GMPase activity level can regulate the sensitivity of Arabidopsis to ammonium [119]. The vtc1-1 mutant exhibits stunted root growth with an elevated of NH4+ efflux at the elongation zone and inhibition of cell elongation in the presence of NH4+ [120], but this NH4+-hypersensitive phenotype in mutant is independent of AsA-deficiency. In fact, the GMP gene disruption can also cause N-glycosylation disorder of proteins associated with the destruction of hormone homeostasis and the increase of nitric oxide content under high NH4+ conditions, consequently leading to conditional sensitivity to ammonium ions [121]. However, impaired GDP-mannose biosynthesis and defective N-glycosylation are required for but are not the primary causes of conditional NH4+ sensitivity in vtc1-1, whereas pH alterations in the presence of NH4+ associated with lost N for assimilation and alkalinization of the cytosol account for the drastic root growth defect in WT and vtc1-1 [122].

5.4. Cellulose-like Synthase A/D (CSLA/D): GDP-Man + UDP/GDP-Glu → Glucomannan

The cellulose synthase gene superfamily consists of the CesA family and 10 Csl families: CslA~CslH, CslJ, and CslM [123,124]. The 30 Arabidopsis CSL proteins is clustered into six families: CslA, CslB, CslC, CslD, CslE, and CslG [125], and the 33 rice CSL proteins are also divided into six families: CslA, CslC, CslD, CslE, CslF, and CslH [126], but only the CslA, CslC, CslD, and CslE families are shared by both. CSL proteins are usually located in the Golgi apparatus, which mediates the synthesis of hemicellulose and then transports it to the cell wall [127]. The CSLA/D families are mainly responsible for the skeleton synthesis of mannan and glucomannan [128,129]. So far, nine CSLA and six CSLD genes have been identified in Arabidopsis, while 10 CSLA and four CSLD genes have been identified in rice [130,131], and 13 CSLA [132] and eight CSLD members have been identified in D. catenatum [21].
Heterologous expression assays showed CSLA proteins from a variety of species catalyze the biosynthesis of the β-1,4-mannan or glucomannan backbone in vitro, such as CtManS in guar (Cyamopsis tetragonoloba) [133], AtCSLA2/7/9 in Arabidopsis [128], OsCSLA1 in rice [134], PtCslA1 in Populus trichocarpa [135], AkCSLA3 in A. konjac [136], and TfManS in fenugreek (Trigonella foenum-graecum) [137]. In Arabidopsis, the csla9 mutant exhibits significantly decreased glucomannan, and the csla2 csla3 csla9 triple mutant is absent of detectable glucomannan in inflorescence stems, although these mutants have no alteration in stem development or strength [138]. The clsa7 mutant is embryo lethal due to defective embryogenesis with evidently delayed development, abnormal cell patterning, and an arrested globular stage, associated with reduced nuclei proliferation and failed cellularization in the endosperm [139]. Overexpression of AtCSLA2, AtCSLA7, and AtCSLA9 leads to elevated glucomannan content in stems; AtCSLA9 overexpression can rescue the embryo lethality of csla7, indicating their functional redundancy [138]. Therefore, AtCSLA2, AtCSLA3, and AtCSLA9 are necessary for glucomannan synthesis in the stem, while AtCSLA7 is necessary for glucomannan synthesis in the embryo [138]. Heterologous expression of the O-fucosyltransferase family member AtMSR1 can enhance the glucomannan synthesis capability of AtCSLA2 and AkCSLA3, possibly via affecting enzymatic activity by protein glycosylation [140,141]. The mannosyl level in stem glucomannans is decreased by around 40% in Arabidopsis msr1 single mutant and by more than 50% in msr1 msr2 double mutant [142]. Transcription factors ANAC041, bZIP1, and MYB46 can directly bind the promoter of AtCLSA9 and regulate its expression [143]. Furthermore, overexpression of MYB46 leads to a significant increase in mannan content. In D. catenatum, overexpression of DoCSLA6 in Arabidopsis promotes mannan biosynthesis [144].
CSLD family members are required for the growth of stem and root, tip growth of root hair and pollen tube, and female gametophyte development and fertility. In Arabidopsis, the csld2 and csld3 mutants exhibit root hair bursts [145,146,147,148]; the csld5 mutant has reduced stem growth [149]; the csld1 and csld4 mutants are defective in male transmission and pollen tube production; the csld2 csld5, csld3, and csld5 and csld2, csld3, and csld5 mutants display dwarfism and severely reduced viability [129]; and csld2 and csld3 show synergid cell degeneration during megagametogenesis and reduced pollen tube penetration during fertilization [150]. In rice, the oscsld4 (nd1) mutant is dwarfed and its culm possesses a decreased content of xylan and cellulose but an increased amount of homogalacturonan, whereas disruption of the Arabidopsis AtCSLD5 gene results in decreased xylan and homogalacturonan synthase activities in Arabidopsis [151]. It seems that CSLD proteins are not only limited in (gluco)mannan biosynthesis. At first, researchers tended to believe that CSLD proteins have major functions in mannan synthesis because microsomes isolated from tobacco (Nicotiana benthamiana) leaves heterologously expressing AtCSLD5 or co-expressing AtCSLD2/3 have elevated mannan synthase activity, specifically using GDP-Man as an activated nucleotide-sugar donor [152]. However, genetic rescue assays with CSLD-CESA chimeric proteins and in vitro biochemical reconstitution suggested that CSLD3 prefers to function as a UDP-Glu-dependent β-1,4-glucan synthase and forms a protein complex displaying a similar ultrastructural feature to the CESA6-forming complex [153,154]. Overexpression of cotton GhCSLD3 in Arabidopsis enhances primary cell wall synthesis and restores the defects of the atceas6 mutant, including significantly reduced cellulose content, a defected cell wall, and a lower dry mass, indicating that GhCSLD3 and AtCESA6 may play a similar role in cellulose or cellulose-like polysaccharide synthesis [155]. Furthermore, the CSLD family is the most similar of the CSL gene families to the CESA family at the amino acid level [125] and, together with the CSLF family (accounting for mixed-linkage glucan synthesis), displays the closest relationship with the CESA family at the phylogeny level [156]. Therefore, the CSLD family might function as both a (gluco)mannan synthase and a β-1,4-glucan synthase.

6. Summary and Perspective

Food production concerns a new hot topic from meeting the need of “eating fully” to “eating healthily” [7,157]. In modern life, dietary structure and habits have changed, and the source of staple food is mostly limited to several starch crops, including rice, wheat, maize, and potatoes, leading to nutrition imbalance and hidden hunger [158]. Furthermore, severe malnutrition will hinder human growth and development, accompanied by mental disorders and diseases [159]. More than 7% of chronic diseases in contemporary society are caused by hidden hunger. The FAO proposed Zero Hunger as the 2nd Sustainable Development Goal to eliminate all forms of hunger by 2030, and biodiversity for food and agriculture is indispensable to achieve the Zero Hunger program [160]. Dietary diversity and a higher intake of dietary fiber can reduce the risk of chronic diseases such as diabetes, obesity, and cardiovascular disease. Intriguingly, D. catenatum as a traditional dual-purpose plant for both food and medicine in China, is able to supple glucomannan as an excellent dietary fiber and has great potential to fight hidden hunger.
The efficiency of D. catenatum is largely dependent on the active polysaccharide glucomannan, which has multiple medicinal effects such as anti-tumor, lowering blood lipids, and preventing diabetes. To date, most of the studies on the glucomannan biosynthetic pathway have focused on its role as a cell wall structural component. PMI, PMM, and GMP sequentially catalyze the production of GDP-mannose, thus providing precursors for the synthesis of glucomannan, and CSLA/D is required for the synthesis of the glucomannan skeleton. However, little is known about the subcellular localization, transportation, and regulation of storage glucomannan, which may be clarified by the comprehensive application of newly developed technologies including immunolocalization, high throughput omics, and gene editing, consequently contributing to creating a glucomannan biofortified crop through synthetic biology (Figure 6). For instance, a stack of four identified committed genes, including manC and manB from Escherichia coli BL21(DE3), manA and pgi from Bacillus subtilis, are introduced into food-grade B. subtilis to obtain mannan [161]. Four anthocyanin synthetic genes, sZmPSY1, sPaCrtI, sCrBKT, and sHpBHY, are introduced into rice endosperm to produce astaxanthin-rich rice with high antioxidant activity [162]. Therefore, it is promising that glucomannan biofortified crops in the future will contribute to reducing hidden hunger and chronic diseases and promoting human health.

Author Contributions

Drafting the manuscript: L.Q. and Y.S.; Gathering data: Y.S.; Contributing to the section of introduction: C.L.; Contributing to the section of feature and structure of glucomannan: J.L.; Contributing to the section of summary and perspective: J.S.; Conceiving the framework: D.C. and Z.H.; Revising the manuscript: S.-L.C. and K.-J.L. All authors have read and agreed to the published version of the manuscript.

Funding

This work was funded by National Natural Science Foundation of China (31870310), and the Major Science and Technology Projects of Breeding New Varieties of Agriculture in Zhejiang Province (2021C02074).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data used to support the findings of this study is available.

Acknowledgments

We appreciate Alexandre Berr (Institut de biologie moléculaire des plantes, France) for language revision.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Si, J.; Zhang, Y.; Luo, Y.; Liu, J.; Liu, Z. Herbal textual research on relationship between chinese medicine “shihu” (Dendrobium spp.) and “tiepi shihu” (D. catenatum). China J. Chin. Mater. Med. 2017, 42, 2001–2005. [Google Scholar]
  2. Cheng, J.; Dang, P.-P.; Zhao, Z.; Yuan, L.-C.; Zhou, Z.-H.; Wolf, D.; Luo, Y.-B. An assessment of the chinese medicinal Dendrobium industry: Supply, demand and sustainability. J. Ethnopharmacol. 2019, 229, 81–88. [Google Scholar] [CrossRef]
  3. Si, J.; Wang, Q.; Liu, Z.; Liu, J.; Luo, Y. Breakthrough in key science and technologies in Dendrobium catenatum Industry. China J. Chin. Mater. Med. 2017, 42, 2223–2227. [Google Scholar]
  4. Jiao, C.; Song, C.; Zheng, S.; Zhu, Y.; Jin, Q.; Cai, Y.; Lin, Y. Metabolic profiling of Dendrobium officinale in response to precursors and methyl jasmonate. Int. J. Mol. Sci. 2018, 19, 728. [Google Scholar] [CrossRef] [Green Version]
  5. Huang, K.; Li, Y.; Tao, S.; Wei, G.; Huang, Y.; Chen, D.; Wu, C. Purification, characterization and biological activity of polysaccharides from Dendrobium officinale. Molecules 2016, 21, 701. [Google Scholar] [CrossRef] [Green Version]
  6. Keithley, J.; Swanson, B. Glucomannan and obesity: A critical review. Altern. Ther. Health Med. 2005, 11, 30–34. [Google Scholar]
  7. Chen, D.; Han, Z.; Si, J. Huangjing (Polygonati rhizoma) is an emerging crop with great potential to fight chronic and hidden hunger. Sci. China Life Sci. 2021, 64, 1564–1566. [Google Scholar] [CrossRef]
  8. Gonzalez, P.S.; O’Prey, J.; Cardaci, S.; Barthet, V.J.A.; Sakamaki, J.; Beaumatin, F.; Roseweir, A.; Gay, D.M.; Mackay, G.; Malviya, G.; et al. Mannose impairs tumour growth and enhances chemotherapy. Nature 2018, 563, 719–723. [Google Scholar] [CrossRef] [Green Version]
  9. Food and Agriculture Organization of the United Nations. Future Smart Food: Rediscovering Hidden Treasures of Neglected and Underutilized Species for Zero Hunger in Asia; Li, X., Siddique, K.H.M., Eds.; UN: Rome, Italy, 2018; ISBN 978-92-1-047392-7. [Google Scholar]
  10. Siddique, K.H.M.; Li, X.; Gruber, K. Rediscovering Asia’s forgotten crops to fight chronic and hidden hunger. Nat. Plants 2021, 7, 116–122. [Google Scholar] [CrossRef]
  11. McCarty, M.F. Glucomannan minimizes the postprandial insulin surge: A potential adjuvant for hepatothermic therapy. Med. Hypotheses 2002, 58, 487–490. [Google Scholar] [CrossRef]
  12. Chua, M.; Hocking, T.J.; Chan, K.; Baldwin, T.C. Temporal and spatial regulation of glucomannan deposition and mobilization in corms of Amorphophallus konjac (Araceae). Am. J. Bot. 2013, 100, 337–345. [Google Scholar] [CrossRef] [PubMed]
  13. Silva, H.; Sagardia, S.; Seguel, O.; Torres, C.; Tapia, C.; Franck, N.; Cardemil, L. Effect of water availability on growth and water use efficiency for biomass and gel production in Aloe Vera (Aloe barbadensis M.). Ind. Crops Prod. 2010, 31, 20–27. [Google Scholar] [CrossRef]
  14. Chen, J.; Li, J.; Li, B. Identification of molecular driving forces involved in the gelation of konjac glucomannan: Effect of degree of deacetylation on hydrophobic association. Carbohydr. Polym. 2011, 86, 865–871. [Google Scholar] [CrossRef]
  15. Cescutti, P.; Campa, C.; Delben, F.; Rizzo, R. Structure of the oligomers obtained by enzymatic hydrolysis of the glucomannan produced by the plant Amorphophallus konjac. Carbohydr. Res. 2002, 337, 2505–2511. [Google Scholar] [CrossRef]
  16. Shi, X.-D.; Nie, S.-P.; Yin, J.-Y.; Que, Z.-Q.; Zhang, L.-J.; Huang, X.-J. Polysaccharide from leaf skin of Aloe barbadensis Miller: Part I. Extraction, fractionation, physicochemical properties and structural characterization. Food Hydrocoll. 2017, 73, 176–183. [Google Scholar] [CrossRef]
  17. Pereira, J.H.; Chen, Z.; McAndrew, R.P.; Sapra, R.; Chhabra, S.R.; Sale, K.L.; Simmons, B.A.; Adams, P.D. Biochemical characterization and crystal structure of endoglucanase Cel5A from the hyperthermophilic Thermotoga maritima. J. Struct. Biol. 2010, 172, 372–379. [Google Scholar] [CrossRef]
  18. Tester, R.; Al-Ghazzewi, F. Glucomannans and nutrition. Food Hydrocoll. 2017, 68, 246–254. [Google Scholar] [CrossRef]
  19. Zhang, C.; Chen, J.; Yang, F. Konjac glucomannan, a promising polysaccharide for OCDDS. Carbohydr. Polym. 2014, 104, 175–181. [Google Scholar] [CrossRef]
  20. Katsuraya, K.; Okuyama, K.; Hatanaka, K.; Oshima, R.; Sato, T.; Matsuzaki, K. Constitution of konjac glucomannan: Chemical analysis and 13C NMR spectroscopy. Carbohydr. Polym. 2003, 53, 183–189. [Google Scholar] [CrossRef]
  21. Xi, H.; Li, Q.; Chen, X.; Liu, C.; Zhao, Y.; Yao, J.; Chen, D.; Liu, J.; Si, J.; Zhang, L. Genome-wide identification of cellulose-like synthase D gene family in Dendrobium catenatum. Biotechnol. Biotechnol. Equip. 2021, 35, 1163–1176. [Google Scholar] [CrossRef]
  22. Li, L.; Yao, H.; Li, X.; Zhang, Q.; Wu, X.; Wong, T.; Zheng, H.; Fung, H.; Yang, B.; Ma, D.; et al. Destiny of Dendrobium officinale Polysaccharide after Oral Administration: Indigestible and Nonabsorbing, Ends in Modulating Gut Microbiota. J. Agric. Food Chem. 2019, 67, 5968–5977. [Google Scholar] [CrossRef] [PubMed]
  23. Luo, Q.L.; Tang, Z.H.; Zhang, X.F.; Wang, L.S.; Lin, C.W.; Luo, X. Isolation, Purification and Chemical Composition Analysis of Polysaccharides from Dendrobium officinale. J. Guangxi Univ. (Nat. Sci. Ed.) 2016, 41, 2060–2066. [Google Scholar]
  24. Hsieh, Y.S.-Y.; Chien, C.; Liao, S.K.-S.; Liao, S.-F.; Hung, W.-T.; Yang, W.-B.; Lin, C.-C.; Cheng, T.-J.R.; Chang, C.-C.; Fang, J.-M.; et al. Structure and bioactivity of the polysaccharides in medicinal plant Dendrobium huoshanense. Bioorg. Med. Chem. 2008, 16, 6054–6068. [Google Scholar] [CrossRef]
  25. Hua, Y.; Zhang, M.; Fu, C.; Chen, Z.; Chan, G.Y.S. Structural characterization of a 2-O-acetylglucomannan from Dendrobium officinale stem. Carbohydr. Res. 2004, 339, 2219–2224. [Google Scholar] [CrossRef] [PubMed]
  26. Gao, Y.; Hu, X.; Wang, Y.; Jiang, Z.; Zhang, H.; Zhang, M.; Hu, P. Primary structural analysis of polysaccharides from Dendrobium officinale. Chem. J. Univ. 2018, 39, 934–940. [Google Scholar]
  27. Kuang, M.-T.; Li, J.-Y.; Yang, X.-B.; Yang, L.; Xu, J.-Y.; Yan, S.; Lv, Y.-F.; Ren, F.-C.; Hu, J.-M.; Zhou, J. Structural characterization and hypoglycemic effect via stimulating glucagon-like peptide-1 secretion of two polysaccharides from Dendrobium officinale. Carbohydr. Polym. 2020, 241, 116326. [Google Scholar] [CrossRef]
  28. Li, M.; Feng, G.; Wang, H.; Yang, R.; Xu, Z.; Sun, Y.-M. Deacetylated konjac glucomannan is less effective in reducing dietary-induced hyperlipidemia and hepatic steatosis in C57BL/6 mice. J. Agric. Food Chem. 2017, 65, 1556–1565. [Google Scholar] [CrossRef]
  29. Tao, S.; Lei, Z.; Huang, K.; Li, Y.; Ren, Z.; Zhang, X.; Wei, G.; Chen, H. Structural characterization and immunomodulatory activity of two novel polysaccharides derived from the stem of Dendrobium officinale Kimura et Migo. J. Funct. Foods 2019, 57, 121–134. [Google Scholar] [CrossRef]
  30. Xing, X.; Cui, S.W.; Nie, S.; Phillips, G.O.; Goff, H.D.; Wang, Q. Study on Dendrobium officinale o-acetyl-glucomannan (dendronan®): Part II. fine structures of o-acetylated residues. Carbohydr. Polym. 2015, 117, 422–433. [Google Scholar] [CrossRef]
  31. Xie, S.-Z.; Liu, B.; Zhang, D.-D.; Zha, X.-Q.; Pan, L.-H.; Luo, J.-P. Intestinal immunomodulating activity and structural characterization of a new polysaccharide from stems of Dendrobium officinale. Food Funct. 2016, 7, 2789–2799. [Google Scholar] [CrossRef]
  32. Wei, W.; Feng, L.; Bao, W.-R.; Ma, D.-L.; Leung, C.-H.; Nie, S.-P.; Han, Q.-B. Structure characterization and immunomodulating effects of polysaccharides isolated from Dendrobium officinale. J. Agric. Food Chem. 2016, 64, 881–889. [Google Scholar] [CrossRef] [PubMed]
  33. Yu, W.; Ren, Z.; Zhang, X.; Xing, S.; Tao, S.; Liu, C.; Wei, G.; Yuan, Y.; Lei, Z. Structural characterization of polysaccharides from Dendrobium officinale and their effects on apoptosis of hela cell line. Molecules 2018, 23, 2484. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  34. Wei, Y.; Wang, L.; Wang, D.; Wang, D.; Wen, C.; Han, B.; Ouyang, Z. Characterization and anti-tumor activity of a polysaccharide isolated from Dendrobium officinale grown in the Huoshan County. Chin. Med. 2018, 13, 47. [Google Scholar] [CrossRef]
  35. Liang, J.; Chen, S.; Hu, Y.; Yang, Y.; Yuan, J.; Wu, Y.; Li, S.; Lin, J.; He, L.; Hou, S.; et al. Protective roles and mechanisms of Dendrobium officinal polysaccharides on secondary liver injury in acute colitis. Int. J. Biol. Macromol. 2018, 107, 2201–2210. [Google Scholar] [CrossRef]
  36. Liu, J.; Yu, L.; Wang, C.; Zhang, Y.; Xi, H.; Si, J.; Zhang, L.; Yan, J. Preparation, structural features and in vitro immunostimulatory activity of a glucomannan from fresh Dendrobium catenatum stems. Front. Nutr. 2022, 8, 823803. [Google Scholar] [CrossRef] [PubMed]
  37. Chen, W.; Wu, J.; Li, X.; Lu, J.; Wu, W.; Sun, Y.; Zhu, B.; Qin, L. Isolation, structural properties, bioactivities of polysaccharides from Dendrobium officinale Kimura et. Migo: A review. Int. J. Biol. Macromol. 2021, 184, 1000–1013. [Google Scholar] [CrossRef]
  38. Chen, H.-L.; Fan, Y.-H.; Chen, M.-E.; Chan, Y. Unhydrolyzed and hydrolyzed konjac glucomannans modulated cecal and fecal microflora in Balb/c mice. Nutrition 2005, 21, 1059–1064. [Google Scholar] [CrossRef] [PubMed]
  39. Behera, S.S.; Ray, R.C. Konjac glucomannan, a promising polysaccharide of Amorphophallus konjac K. Koch in health care. Int. J. Biol. Macromol. 2016, 92, 942–956. [Google Scholar] [CrossRef]
  40. Holscher, H.D. Dietary fiber and prebiotics and the gastrointestinal microbiota. Gut Microbes 2017, 8, 172–184. [Google Scholar] [CrossRef]
  41. Nakamura, Y.K.; Omaye, S.T. Metabolic diseases and pro- and prebiotics: Mechanistic insights. Nutr. Metab. 2012, 9, 60. [Google Scholar] [CrossRef] [Green Version]
  42. Colantonio, A.G.; Werner, S.L.; Brown, M. The Effects of prebiotics and substances with prebiotic properties on metabolic and inflammatory biomarkers in individuals with type 2 diabetes mellitus: A systematic review. J. Acad. Nutr. Diet. 2020, 120, 587–607.e2. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  43. Tanabe, K.; Nakamura, S.; Moriyama-Hashiguchi, M.; Kitajima, M.; Ejima, H.; Imori, C.; Oku, T. Dietary fructooligosaccharide and glucomannan alter gut microbiota and improve bone metabolism in senescence-accelerated mouse. J. Agric. Food Chem. 2019, 67, 867–874. [Google Scholar] [CrossRef] [PubMed]
  44. Connolly, M.L.; Lovegrove, J.A.; Tuohy, K.M. Konjac glucomannan hydrolysate beneficially modulates bacterial composition and activity within the faecal microbiota. J. Funct. Foods 2010, 2, 219–224. [Google Scholar] [CrossRef]
  45. Al-Ghazzewi, F.H.; Khanna, S.; Tester, R.F.; Piggott, J. The potential use of hydrolysed konjac glucomannan as a prebiotic. J. Sci. Food Agric. 2007, 87, 1758–1766. [Google Scholar] [CrossRef]
  46. Lu, Y.; Zhang, J.; Zhang, Z.; Liang, X.; Liu, T.; Yi, H.; Gong, P.; Wang, L.; Yang, W.; Zhang, X.; et al. Konjac glucomannan with probiotics acts as a combination laxative to relieve constipation in mice by increasing short-chain fatty acid metabolism and 5-hydroxytryptamine hormone release. Nutrition 2021, 84, 111112. [Google Scholar] [CrossRef]
  47. Pongsapipatana, N.; Charoenwattanasatien, R.; Pramanpol, N.; Nguyen, T.-H.; Haltrich, D.; Nitisinprasert, S.; Keawsompong, S. Crystallization, structural characterization and kinetic analysis of a GH26 β-mannanase from Klebsiella oxytoca KUB-CW2-3. Acta Crystallogr. Sect. Struct. Biol. 2021, 77, 1425–1436. [Google Scholar] [CrossRef]
  48. Li, J.; Jiao, G.; Sun, Y.; Chen, J.; Zhong, Y.; Yan, L.; Jiang, D.; Ma, Y.; Xia, L. Modification of starch composition, structure and properties through editing of TaSBEIIa in both winter and spring wheat varieties by CRISPR/Cas9. Plant Biotechnol. J. 2021, 19, 937–951. [Google Scholar] [CrossRef]
  49. Zhang, Y.; Wu, Z.; Liu, J.; Zheng, Z.; Li, Q.; Wang, H.; Chen, Z.; Wang, K. Identification of the core active structure of a Dendrobium officinale polysaccharide and its protective effect against dextran sulfate sodium-induced colitis via alleviating gut microbiota dysbiosis. Food Res. Int. 2020, 137, 109641. [Google Scholar] [CrossRef]
  50. Rooks, M.G.; Garrett, W.S. Gut Microbiota, Metabolites and host immunity. Nat. Rev. Immunol. 2016, 16, 341–352. [Google Scholar] [CrossRef]
  51. Zhang, L.-J.; Huang, X.-J.; Shi, X.-D.; Chen, H.-H.; Cui, S.W.; Nie, S.-P. Protective effect of three glucomannans from different plants against DSS induced colitis in female BALB/c mice. Food Funct. 2019, 10, 1928–1939. [Google Scholar] [CrossRef]
  52. Zhang, K.; Zhou, X.; Wang, J.; Zhou, Y.; Qi, W.; Chen, H.; Nie, S.; Xie, M. Dendrobium officinale polysaccharide triggers mitochondrial disorder to induce colon cancer cell death via ROS-AMPK-autophagy pathway. Carbohydr. Polym. 2021, 264, 118018. [Google Scholar] [CrossRef] [PubMed]
  53. Zhu, J. T helper 2 (Th2) cell differentiation, type 2 innate lymphoid cell (ILC2) development and regulation of interleukin-4 (IL-4) and IL-13 production. Cytokine 2015, 75, 14–24. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  54. Zhong, C.; Tian, W.; Chen, H.; Yang, Y.; Xu, Y.; Chen, Y.; Chen, P.; Zhu, S.; Li, P.; Du, B. Structural characterization and immunoregulatory activity of polysaccharides from Dendrobium officinale leaves. J. Food Biochem. 2022, 46, e14023. [Google Scholar] [CrossRef] [PubMed]
  55. Gurusmatika, S.; Nishi, K.; Harmayani, E.; Pranoto, Y.; Sugahara, T. Immunomodulatory activity of octenyl succinic anhydride modified porang (Amorphophallus oncophyllus) glucomannan on mouse macrophage-like J774.1 cells and mouse primary peritoneal macrophages. Molecules 2017, 22, 1187. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  56. Jo, K.; Kim, S.; Yu, K.; Chung, Y.B.; Kim, W.J.; Suh, H.J.; Kim, H. Changes in the component sugar and immunostimulating activity of polysaccharides isolated from Dendrobium officinale in the pretreatments. J. Sci. Food Agric. 2022, 102, 3021–3028. [Google Scholar] [CrossRef] [PubMed]
  57. Tao, S.; Ren, Z.; Yang, Z.; Duan, S.; Wan, Z.; Huang, J.; Liu, C.; Wei, G. Effects of different molecular weight polysaccharides from Dendrobium officinale kimura & migo on human colorectal cancer and transcriptome analysis of differentially expressed genes. Front. Pharmacol. 2021, 12, 704486. [Google Scholar] [CrossRef]
  58. Porta, C.; Paglino, C.; Mosca, A. Targeting PI3K/Akt/mTOR signaling in cancer. Front. Oncol. 2014, 4, 00064. [Google Scholar] [CrossRef] [Green Version]
  59. Guanen, Q.; Junjie, S.; Baolin, W.; Chaoyang, W.; Yajuan, Y.; Jing, L.; Junpeng, L.; Gaili, N.; Zhongping, W.; Jun, W. MiR-214 promotes cell meastasis and inhibites apoptosis of esophageal squamous cell carcinoma via PI3K/AKT/mTOR signaling pathway. Biomed. Pharmacother. 2018, 105, 350–361. [Google Scholar] [CrossRef]
  60. Wu, C.; Qiu, S.; Liu, P.; Ge, Y.; Gao, X. Rhizoma Amorphophalli inhibits TNBC cell proliferation, migration, invasion and metastasis through the PI3K/Akt/mTOR pathway. J. Ethnopharmacol. 2018, 211, 89–100. [Google Scholar] [CrossRef]
  61. Liang, J.; Li, H.; Chen, J.; He, L.; Du, X.; Zhou, L.; Xiong, Q.; Lai, X.; Yang, Y.; Huang, S.; et al. Dendrobium officinale polysaccharides alleviate colon tumorigenesis via restoring intestinal barrier function and enhancing anti-tumor immune response. Pharmacol. Res. 2019, 148, 104417. [Google Scholar] [CrossRef]
  62. Zhao, Y.; Li, B.; Wang, G.; Ge, S.; Lan, X.; Xu, G.; Liu, H. Dendrobium officinale polysaccharides inhibit 1-methyl-2-nitro-1-nitrosoguanidine induced precancerous lesions of gastric cancer in rats through regulating wnt/β-catenin pathway and altering serum endogenous metabolites. Molecules 2019, 24, 2660. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  63. Han, H.; Liu, W.; Chen, F.; Li, N. Effects of Dendrobium officinale polysaccharide on AMPK/ULK1 Pathway Related Autophagy in Astrocytes Induced by Hypoxia/Reoxygenation. China J. Mod. Appl. Pharm. 2021, 38, 2101–2115. [Google Scholar]
  64. Liu, Y.; Yang, L.; Zhang, Y.; Liu, X.; Wu, Z.; Gilbert, R.G.; Deng, B.; Wang, K. Dendrobium officinale polysaccharide ameliorates diabetic hepatic glucose metabolism via glucagon-mediated signaling pathways and modifying liver-glycogen structure. J. Ethnopharmacol. 2020, 248, 112308. [Google Scholar] [CrossRef] [PubMed]
  65. Chen, H.; Nie, Q.; Hu, J.; Huang, X.; Huang, W.; Nie, S. Metabolism amelioration of Dendrobium officinale polysaccharide on type II diabetic rats. Food Hydrocoll. 2020, 102, 105582. [Google Scholar] [CrossRef]
  66. Wang, K.; Wang, H.; Liu, Y.; Shui, W.; Wang, J.; Cao, P.; Wang, H.; You, R.; Zhang, Y. Dendrobium officinale polysaccharide attenuates type 2 diabetes mellitus via the regulation of PI3K/Akt-mediated glycogen synthesis and glucose metabolism. J. Funct. Foods 2018, 40, 261–271. [Google Scholar] [CrossRef]
  67. Chen, J.; Wan, L.; Zheng, Q.; Lan, M.; Zhang, X.; Li, Y.; Li, B.; Li, L. Structural characterization and in vitro hypoglycaemic activity of glucomannan from Anemarrhena asphodeloides bunge. Food Funct. 2022, 13, 1797–1807. [Google Scholar] [CrossRef]
  68. Walsh, D.E.; Yaghoubian, V.; Behforooz, A. Effect of glucomannan on obese patients: A clinical study. Int. J. Obes. 1984, 8, 289–293. [Google Scholar]
  69. Li, Q.; Xie, C.; Li, X.; Wang, X. Chemical constituents of Dendrobium officinale and their development and utilization in cosmetics. China Surfactant Deterg. Cosmet. 2017, 47, 109–113. [Google Scholar]
  70. Chen, M.; Sun, Y.; Zhao, Y. Study on moisturizing properties of Dendrobium officinale extract. J Shanghai Uni Tradit. Chin Med. 2015, 29, 70–73. [Google Scholar] [CrossRef]
  71. Bao, S.; Zha, X.; Hao, J.; Luo, J. Study on antioxidant activity of polysaccharide from Dendrobium officinale with different molecular weight in vitro. Food Sci 2009, 30, 123–127. [Google Scholar]
  72. Luo, Q.; Tang, Z.; Zhang, X.; Zhong, Y.; Yao, S.; Wang, L.; Lin, C.; Luo, X. Chemical properties and antioxidant activity of a water-soluble polysaccharide from Dendrobium officinale. Int. J. Biol. Macromol. 2016, 89, 219–227. [Google Scholar] [CrossRef] [PubMed]
  73. Huang, X.; Han, Z.; Zhang, J. Effects of fermentation on active constituents of Dendrobium officinale and its application in cosmetics. China Surfactant Deterg. 2021, 44, 46–50. [Google Scholar]
  74. Gu, F.; Jiang, X.; Chen, Y.; Han, B.; Chen, N.; Wei, C. Study on hygroscopic and moisturizing properties and skin irritation of polysaccharides from Dendrobium huoshanense. Nat. Prod. Res. Dev. 2018, 30, 1701–1705. [Google Scholar] [CrossRef]
  75. Jiang, W.; Zhou, M.; Li, C.; Zhang, Z.; He, S. Development of functional yoghurt of Dendrobium officinale. Fujian Agric. Sci. Technol. 2021, 51, 19–23. [Google Scholar] [CrossRef]
  76. Meng, Y.; Lu, H.; Yang, S.; Zhang, Z.; Chen, L.; Liu, B.; Wang, L. Preparation technology and function of Dendrobium officinale mixed flower tea. Food Ferment. Ind. 2021, 47, 170–179. [Google Scholar] [CrossRef]
  77. Luo, M.; Xie, W. Development of Dendrobium officinale leaf health tea bag. Food Ind. 2021, 42, 38–43. [Google Scholar]
  78. Tang, W.; Xia, J.; Chen, Y. Effects of different cutting methods on active components and antioxidant activity of Dendrobium officinale leaf tea. Food Sci. Technol. 2021, 46, 74–82. [Google Scholar] [CrossRef]
  79. Chen, S.; Yan, M.; Lv, G.; Liu, X. Development status and progress of Dendrobium officinale health food. Chin. J. Pharm. 2013, 48, 1625–1628. [Google Scholar]
  80. Tan, Y.; Liu, X.; Yuan, F. Structure, properties and application of Konjac Glucomannan in Food. China Condiment 2019, 44, 168–174+178. [Google Scholar]
  81. Baianu, I.C.; Ozu, E.M. Gelling mechanisms of glucomannan polysaccharides and their interactions with proteins. ACS 2002, 8, 298–305. [Google Scholar]
  82. Xue, H.; Wu, D.; Xu, Q.; Zhu, Y.; Cheng, C. Application and research progress of Konjac Glucomannan in yogurt. Packag. Food Mach. 2021, 39, 58–62. [Google Scholar]
  83. Chen, J.; Zhang, K.; Du, J.; Hu, Y.; Wang, L.; Wang, C.; Ni, X.; Jiang, F. Effects of konjac glucomannan and its derivatives on the physical properties of poultry reconstituted ham. Food Sci. 2010, 31, 36–39. [Google Scholar]
  84. Zhao, D.; Zhou, Y.; Liu, H.; Liang, J.; Cheng, Y.; Nirasawa, S. Effects of dough mixing time before adding konjac glucomannan on the quality of noodles. J. Food Sci. Technol. 2017, 54, 3837–3846. [Google Scholar] [CrossRef] [PubMed]
  85. Huang, Y.; Zhang, Y.; Xu, X.; Zhong, G. Optimization of konjac glucomannan edible film formulation. Sci. Technol. Food Ind. 2016, 37, 330–336. [Google Scholar] [CrossRef]
  86. Gilbert, L.; Alhagdow, M.; Nunes-Nesi, A.; Quemener, B.; Guillon, F.; Bouchet, B.; Faurobert, M.; Gouble, B.; Page, D.; Garcia, V.; et al. GDP-d-mannose 3,5-epimerase (GME) plays a key role at the intersection of ascorbate and non-cellulosic cell-wall biosynthesis in tomato. Plant J. 2009, 60, 499–508. [Google Scholar] [CrossRef]
  87. Joët, T.; Laffargue, A.; Salmona, J.; Doulbeau, S.; Descroix, F.; Bertrand, B.; Lashermes, P.; Dussert, S. Regulation of galactomannan biosynthesis in coffee seeds. J. Exp. Bot. 2014, 65, 323–337. [Google Scholar] [CrossRef]
  88. Manzoor, S.; Wani, S.M.; Ahmad Mir, S.; Rizwan, D. Role of probiotics and prebiotics in mitigation of different diseases. Nutrition 2022, 96, 111602. [Google Scholar] [CrossRef]
  89. Chen, C.; Chen, H.; Zhang, Y.; Thomas, H.R.; Frank, M.H.; He, Y.; Xia, R. TBtools: An integrative toolkit developed for interactive analyses of big biological data. Mol. Plant 2020, 13, 1194–1202. [Google Scholar] [CrossRef]
  90. Roux, C.; Gresh, N.; Perera, L.E.; Piquemal, J.-P.; Salmon, L. Binding of 5-phospho-D-arabinonohydroxamate and 5-phospho-D-arabinonate inhibitors to zinc phosphomannose isomerase fromCandida albicans studied by polarizable molecular mechanics and quantum mechanics. J. Comput. Chem. 2007, 28, 938–957. [Google Scholar] [CrossRef]
  91. Wheeler, G.L.; Jones, M.A.; Smirnoff, N. The biosynthetic pathway of vitamin C in higher plants. Natre 1998, 393, 365–369. [Google Scholar] [CrossRef]
  92. Maruta, T.; Yonemitsu, M.; Yabuta, Y.; Tamoi, M.; Ishikawa, T.; Shigeoka, S. Arabidopsis Phosphomannose isomerase 1, but not phosphomannose isomerase 2, is essential for ascorbic acid biosynthesis. J. Biol. Chem. 2008, 283, 28842–28851. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  93. Xiao, M.; Li, Z.; Zhu, L.; Wang, J.; Zhang, B.; Zheng, F.; Zhao, B.; Zhang, H.; Wang, Y.; Zhang, Z. The multiple roles of ascorbate in the abiotic stress response of plants: Antioxidant, cofactor, and regulator. Front. Plant Sci. 2021, 12, 598173. [Google Scholar] [CrossRef] [PubMed]
  94. Wang, X.; Zhang, S.; Hu, D.; Zhao, X.; Li, Y.; Liu, T.; Wang, J.; Hou, X.; Li, Y. BcPMI2, isolated from non-heading Chinese cabbage encoding phosphomannose isomerase, improves stress tolerance in transgenic tobacco. Mol. Biol. Rep. 2014, 41, 2207–2216. [Google Scholar] [CrossRef] [PubMed]
  95. Zhu, Y.J.; Agbayani, R.; McCafferty, H.; Albert, H.H.; Moore, P.H. Effective selection of transgenic papaya plants with the PMI/Man selection system. Plant Cell Rep. 2005, 24, 426–432. [Google Scholar] [CrossRef]
  96. He, Z.; Fu, Y.; Si, H.; Hu, G.; Zhang, S.; Yu, Y.; Sun, Z. Phosphomannose-isomerase (PMI) gene as a selectable marker for rice transformation via Agrobacterium. Plant Sci. 2004, 166, 17–22. [Google Scholar] [CrossRef]
  97. Fujiki, Y.; Yoshikawa, Y.; Sato, T.; Inada, N.; Ito, M.; Nishida, I.; Watanabe, A. Dark-inducible genes from Arabidopsis thaliana are associated with leaf senescence and repressed by sugars. Physiol. Plant. 2001, 111, 345–352. [Google Scholar] [CrossRef]
  98. Wang, T.; Liu, L.; Tang, Y.; Zhang, X.; Zhang, M.; Zheng, Y.; Zhang, F. Using the phosphomannose isomerase (PMI) gene from saccharomyces cerevisiae for selection in rice transformation. J. Integr. Agric. 2012, 11, 1391–1398. [Google Scholar] [CrossRef]
  99. Duan, Y.; Zhai, C.; Li, H.; Li, J.; Mei, W.; Gui, H.; Ni, D.; Song, F.; Li, L.; Zhang, W.; et al. An efficient and high-throughput protocol for Agrobacterium-mediated transformation based on phosphomannose isomerase positive selection in Japonica rice (Oryza sativa L.). Plant Cell Rep. 2012, 31, 1611–1624. [Google Scholar] [CrossRef]
  100. Hu, L.; Li, H.; Qin, R.; Xu, R.; Li, J.; Li, L.; Wei, P.; Yang, J. Plant phosphomannose isomerase as a selectable marker for rice transformation. Sci. Rep. 2016, 6, 25921. [Google Scholar] [CrossRef] [Green Version]
  101. Joersbo, M.; Donaldson, I.; Kreiberg, J.; Petersen, S.G.; Brunstedt, J.; Okkels, F.T. Analysis of mannose selection used for transformation of sugar beet. Mol. Breed. 1998, 4, 111–117. [Google Scholar] [CrossRef]
  102. Miki, B.; McHugh, S. Selectable marker genes in transgenic plants: Applications, alternatives and biosafety. J. Biotechnol. 2004, 107, 193–232. [Google Scholar] [CrossRef] [PubMed]
  103. Lin, Y.; Huang, J. Characterization of an algal phosphomannose isomerase gene and its application as a selectable marker for genetic manipulation of tomato. Plant Divers. 2021, 43, 63–70. [Google Scholar] [CrossRef] [PubMed]
  104. Small, D.M.; Matheson, N.K. Phosphomannomutase and phosphoglucomutase in developing Cassia corymbosa seeds. Phytochemistry 1979, 18, 1147–1150. [Google Scholar] [CrossRef]
  105. Qian, W.; Yu, C.; Qin, H.; Liu, X.; Zhang, A.; Johansen, I.E.; Wang, D. Molecular and functional analysis of phosphomannomutase (PMM) from higher plants and genetic evidence for the involvement of PMM in ascorbic acid biosynthesis in Arabidopsis and Nicotiana benthamiana: Functional analysis of plant phosphomannomutase. Plant J. 2007, 49, 399–413. [Google Scholar] [CrossRef] [PubMed]
  106. Badejo, A.A.; Fujikawa, Y.; Esaka, M. Gene expression of ascorbic acid biosynthesis related enzymes of the Smirnoff-Wheeler pathway in acerola (Malpighia glabra). J. Plant Physiol. 2009, 166, 652–660. [Google Scholar] [CrossRef] [PubMed]
  107. Gao, L.; Xia, Z.; Zhang, J.; Wang, D.; Zhai, W. Transgenosis of the phosphomannomutase transgene increases vitamin C content in rice. Chin. J. Rice Sci. 2016, 30, 441–446. [Google Scholar]
  108. He, C.; Zeng, S.; Teixeira da Silva, J.A.; Yu, Z.; Tan, J.; Duan, J. Molecular cloning and functional analysis of the phosphomannomutase (PMM) gene from Dendrobium officinale and evidence for the involvement of an abiotic stress response during germination. Protoplasma 2017, 254, 1693–1704. [Google Scholar] [CrossRef]
  109. Veljovic-Jovanovic, S.D.; Pignocchi, C.; Noctor, G.; Foyer, C.H. Low ascorbic acid in the vtc-1 mutant of Arabidopsis is associated with decreased growth and intracellular redistribution of the antioxidant system. Plant Physiol. 2001, 127, 426–435. [Google Scholar] [CrossRef]
  110. Sawake, S.; Tajima, N.; Mortimer, J.C.; Lao, J.; Ishikawa, T.; Yu, X.; Yamanashi, Y.; Yoshimi, Y.; Kawai-Yamada, M.; Dupree, P.; et al. Konjac1 and 2 are key factors for gdp-mannose generation and affect l-ascorbic acid and glucomannan biosynthesis in Arabidopsis. Plant Cell 2015, 27, 3397–3409. [Google Scholar] [CrossRef]
  111. Badejo, A.A.; Tanaka, N.; Esaka, M. Analysis of GDP-D-mannose pyrophosphorylase gene promoter from Acerola (Malpighia glabra) and increase in ascorbate content of transgenic tobacco expressing the Acerola gene. Plant Cell Physiol. 2008, 49, 126–132. [Google Scholar] [CrossRef] [Green Version]
  112. Cronje, C.; George, G.M.; Fernie, A.R.; Bekker, J.; Kossmann, J.; Bauer, R. Manipulation of l-ascorbic acid biosynthesis pathways in Solanum lycopersicum: Elevated GDP-mannose pyrophosphorylase activity enhances l-ascorbate levels in red fruit. Planta 2012, 235, 553–564. [Google Scholar] [CrossRef] [PubMed]
  113. Wang, H.; Yu, C.; Zhu, Z.; Yu, X. Overexpression in tobacco of a tomato gmpase gene improves tolerance to both low and high temperature stress by enhancing antioxidation capacity. Plant Cell Rep. 2011, 31, 2068–2075. [Google Scholar] [CrossRef] [PubMed]
  114. Zhang, C.; Ouyang, B.; Yang, C.; Zhang, X.; Liu, H.; Zhang, Y.; Zhang, J.; Li, H.; Ye, Z. Reducing AsA leads to leaf lesion and defence response in knock-down of the AsA biosynthetic enzyme GDP-D-mannose pyrophosphorylase gene in tomato plant. PLoS ONE 2013, 8, e61987. [Google Scholar] [CrossRef] [Green Version]
  115. Li, C.; Zhang, L.; Shi, Q.; Li, Q.; Guo, X.; Li, X.; Yu, X. Effect of Tomato GMPase overexpression on tolerance of potato plants to temperature stress. Scientia. Agric. Sin. 2011, 38, 692–700. [Google Scholar]
  116. Ai, T.; Liao, X.; Li, R.; Fan, L.; Luo, F.; Xu, Y.; Wang, S. GDP-D-mannose pyrophosphorylase from Pogonatherum paniceum enhances salinity and drought tolerance of transgenic tobacco. Z. Für Nat. C 2016, 71, 243–252. [Google Scholar] [CrossRef]
  117. He, C.; Yu, Z.; Teixeira da Silva, J.A.; Zhang, J.; Liu, X.; Wang, X.; Zhang, X.; Zeng, S.; Wu, K.; Tan, J.; et al. DoGMP1 from Dendrobium officinale contributes to mannose content of water-soluble polysaccharides and plays a role in salt stress response. Sci. Rep. 2017, 7, 41010. [Google Scholar] [CrossRef] [Green Version]
  118. Huang, C.; He, W.; Guo, J.; Chang, X.; Su, P.; Zhang, L. Increased sensitivity to salt stress in an ascorbate-deficient Arabidopsis mutant. J. Exp. Bot. 2005, 56, 3041–3049. [Google Scholar] [CrossRef] [Green Version]
  119. Qin, C.; Qian, W.; Wang, W.; Wu, Y.; Yu, C.; Jiang, X.; Wang, D.; Wu, P. GDP-mannose pyrophosphorylase is a genetic determinant of ammonium sensitivity in Arabidopsis thaliana. Proc. Natl. Acad. Sci. USA 2008, 105, 18308–18313. [Google Scholar] [CrossRef]
  120. Li, Q.; Li, B.-H.; Kronzucker, H.J.; Shi, W.-M. Root growth inhibition by NH4+ in Arabidopsis is mediated by the root tip and is linked to NH4+ efflux and GMPase activity: Root growth inhibition by ammonium. Plant Cell Environ. 2010, 33, 1529–1542. [Google Scholar] [CrossRef]
  121. Barth, C.; Gouzd, Z.A.; Steele, H.P.; Imperio, R.M. A mutation in GDP-mannose pyrophosphorylase causes conditional hypersensitivity to ammonium, resulting in Arabidopsis root growth inhibition, altered ammonium metabolism, and hormone homeostasis. J. Exp. Bot. 2010, 61, 379–394. [Google Scholar] [CrossRef] [Green Version]
  122. Kempinski, C.F.; Haffar, R.; Barth, C. Toward the mechanism of NH4+ sensitivity mediated by Arabidopsis GDP-mannose pyrophosphorylase: NH4+ sensitivity mediated by GMPase. Plant Cell Environ. 2011, 34, 847–858. [Google Scholar] [CrossRef] [PubMed]
  123. Yin, Y.; Huang, J.; Xu, Y. The cellulose synthase superfamily in fully sequenced plants and algae. BMC Plant Biol. 2009, 9, 99. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  124. Little, A.; Schwerdt, J.G.; Shirley, N.J.; Khor, S.F.; Neumann, K.; O’Donovan, L.A.; Lahnstein, J.; Collins, H.M.; Henderson, M.; Fincher, G.B.; et al. Revised Phylogeny of the Cellulose Synthase Gene Superfamily: Insights into Cell Wall Evolution. Plant Physiol. 2018, 177, 1124–1141. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  125. Richmond, T.A.; Somerville, C.R. The cellulose synthase superfamily. Plant Physiol. 2000, 124, 495–498. [Google Scholar] [CrossRef] [Green Version]
  126. Keegstra, K.; Walton, J. β-glucans--brewer’s bane, dietician’s delight. Science 2006, 311, 1872–1873. [Google Scholar] [CrossRef]
  127. Davis, J.; Brandizzi, F.; Liepman, A.H.; Keegstra, K. Arabidopsis mannan synthase CSLA9 and glucan synthase CSLC4 have opposite orientations in the Golgi membrane: Hemicellulosic glycan synthase topology. Plant J. 2010, 64, 1028–1037. [Google Scholar] [CrossRef]
  128. Liepman, A.H.; Wilkerson, C.G.; Keegstra, K. Expression of cellulose synthase-like (Csl) genes in insect cells reveals that CslA family members encode mannan synthases. Proc. Natl. Acad. Sci. USA 2005, 102, 2221–2226. [Google Scholar] [CrossRef] [Green Version]
  129. Yin, L.; Verhertbruggen, Y.; Oikawa, A.; Manisseri, C.; Knierim, B.; Prak, L.; Jensen, J.K.; Knox, J.P.; Auer, M.; Willats, W.G.T.; et al. The Cooperative activities of CSLD2, CSLD3, and CSLD5 Are required for normal arabidopsis development. Mol. Plant 2011, 4, 1024–1037. [Google Scholar] [CrossRef]
  130. Wang, X.; Cnops, G.; Vanderhaeghen, R.; Block, S.D.; Montagu, M.V.; Lijsebettens, M.V. AtCSLD3, a cellulose synthase-like gene important for root hair growth in Arabidopsis. Plant Physiol. 2001, 126, 575–586. [Google Scholar] [CrossRef] [Green Version]
  131. Hazen, S.P.; Scott-Craig, J.S.; Walton, J.D. Cellulose synthase-like genes of rice. Plant Physiol. 2002, 128, 336–340. [Google Scholar] [CrossRef]
  132. Gao, Y.; Chen, X.; Chen, D.; Liu, J.; Si, J. Genome-wide identification and expression analysis of CSLA gene family of Dendrobium catenatum. China J. Chin Mater. Med. 2020, 45, 3120–3127. [Google Scholar]
  133. Dhugga, K.S.; Barreiro, R.; Whitten, B.; Stecca, K.; Hazebroek, J.; Randhawa, G.S.; Dolan, M.; Kinney, A.J.; Tomes, D.; Nichols, S.; et al. Guar Seed ß-Mannan Synthase Is a Member of the Cellulose Synthase Super Gene Family. Science 2004, 303, 363–366. [Google Scholar] [CrossRef] [PubMed]
  134. Liepman, A.H.; Nairn, C.J.; Willats, W.G.T.; Sørensen, I.; Roberts, A.W.; Keegstra, K. Functional genomic analysis supports conservation of function among cellulose synthase-like A gene family members and suggests diverse roles of mannans in plants. Plant Physiol. 2007, 143, 1881–1893. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  135. Suzuki, S.; Li, L.; Sun, Y.-H.; Chiang, V.L. The Cellulose Synthase Gene superfamily and biochemical functions of xylem-specific cellulose synthase-like genes in Populus trichocarpa. Plant Physiol. 2006, 142, 1233–1245. [Google Scholar] [CrossRef] [Green Version]
  136. Gille, S.; Cheng, K.; Skinner, M.E.; Liepman, A.H.; Wilkerson, C.G.; Pauly, M. Deep sequencing of voodoo lily (Amorphophallus konjac): An approach to identify relevant genes involved in the synthesis of the hemicellulose glucomannan. Planta 2011, 234, 515–526. [Google Scholar] [CrossRef] [Green Version]
  137. Wang, Y.; Alonso, A.P.; Wilkerson, C.G.; Keegstra, K. Deep EST profiling of developing fenugreek endosperm to investigate galactomannan biosynthesis and its regulation. Plant Mol. Biol. 2012, 79, 243–258. [Google Scholar] [CrossRef] [Green Version]
  138. Goubet, F.; Barton, C.J.; Mortimer, J.C.; Yu, X.; Zhang, Z.; Miles, G.P.; Richens, J.; Liepman, A.H.; Seffen, K.; Dupree, P. Cell wall glucomannan in Arabidopsis is synthesised by CSLA glycosyltransferases, and influences the progression of embryogenesis. Plant J. 2009, 60, 527–538. [Google Scholar] [CrossRef]
  139. Goubet, F.; Misrahi, A.; Park, S.K.; Zhang, Z.; Twell, D.; Dupree, P. AtCSLA7, a cellulose synthase-like putative glycosyltransferase, is important for pollen tube growth and embryogenesis in Arabidopsis. Plant Physiol. 2003, 131, 547–557. [Google Scholar] [CrossRef] [Green Version]
  140. Voiniciuc, C.; Dama, M.; Gawenda, N.; Stritt, F.; Pauly, M. Mechanistic insights from plant heteromannan synthesis in yeast. Proc. Natl. Acad. Sci. USA 2019, 116, 522–527. [Google Scholar] [CrossRef]
  141. Robert, M.; Waldhauer, J.; Stritt, F.; Yang, B.; Pauly, M.; Voiniciuc, C. Modular biosynthesis of plant hemicellulose and its impact on yeast cells. Biotechnol. Biofuels 2021, 14, 140. [Google Scholar] [CrossRef]
  142. Wang, Y.; Mortimer, J.C.; Davis, J.; Dupree, P.; Keegstra, K. Identification of an additional protein involved in mannan biosynthesis. Plant J. 2013, 73, 105–117. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  143. Kim, W.-C.; Reca, I.-B.; Kim, Y.; Park, S.; Thomashow, M.F.; Keegstra, K.; Han, K.-H. Transcription factors that directly regulate the expression of CSLA9 encoding mannan synthase in Arabidopsis thaliana. Plant Mol. Biol. 2014, 84, 577–587. [Google Scholar] [CrossRef] [PubMed]
  144. He, C.; Wu, K.; Zhang, J.; Liu, X.; Zeng, S.; Yu, Z.; Zhang, X.; Teixeira da Silva, J.A.; Deng, R.; Tan, J.; et al. Cytochemical localization of polysaccharides in Dendrobium officinale and the involvement of DoCSLA6 in the synthesis of mannan polysaccharides. Front. Plant Sci. 2017, 8, 00173. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  145. Bernal, A.J.; Yoo, C.-M.; Mutwil, M.; Jensen, J.K.; Hou, G.; Blaukopf, C.; Sørensen, I.; Blancaflor, E.B.; Scheller, H.V.; Willats, W.G.T. Functional analysis of the cellulose synthase-like genes CSLD1, CSLD2, and CSLD4 in tip-growing Arabidopsis cells. Plant Physiol. 2008, 148, 1238–1253. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  146. Schnall, J.A.; Quatrano, R.S. Abscisic acid elicits the water-stress response in root hairs of Arabidopsis thaliana. Plant Physiol. 1992, 100, 216–218. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  147. Favery, B.; Ryan, E.; Foreman, J.; Linstead, P.; Boudonck, K.; Steer, M.; Shaw, P.; Dolan, L. KOJAK encodes a cellulose synthase-like protein required for root hair cell morphogenesis in Arabidopsis. Genes Dev. 2001, 15, 79–89. [Google Scholar] [CrossRef] [Green Version]
  148. Galway, M.E.; Eng, R.C.; Schiefelbein, J.W.; Wasteneys, G.O. Root hair-specific disruption of cellulose and xyloglucan in AtCSLD3 mutants, and factors affecting the post-rupture resumption of mutant root hair growth. Planta 2011, 233, 985–999. [Google Scholar] [CrossRef]
  149. Bernal, A.J.; Jensen, J.K.; Harholt, J.; Sørensen, S.; Moller, I.; Blaukopf, C.; Johansen, B.; de Lotto, R.; Pauly, M.; Scheller, H.V.; et al. Disruption of ATCSLD5 results in reduced growth, reduced xylan and homogalacturonan synthase activity and altered xylan occurrence in Arabidopsis. Plant J. 2007, 52, 791–802. [Google Scholar] [CrossRef]
  150. Yoo, C.-M.; Quan, L.; Blancaflor, E.B. Divergence and redundancy in CSLD2 and CSLD3 function during Arabidopsis Thaliana root hair and female gametophyte development. Front. Plant Sci. 2012, 3, 00111. [Google Scholar] [CrossRef]
  151. Li, M.; Xiong, G.; Li, R.; Cui, J.; Tang, D.; Zhang, B.; Pauly, M.; Cheng, Z.; Zhou, Y. Rice cellulose synthase-like D4 is essential for normal cell-wall biosynthesis and plant growth: Rice cellulose synthase-like D4 is essential for normal cell-wall. Plant J. 2009, 60, 1055–1069. [Google Scholar] [CrossRef]
  152. Verhertbruggen, Y.; Yin, L.; Oikawa, A.; Scheller, H.V. Mannan synthase activity in the CSLD family. Plant Signal. Behav. 2011, 6, 1620–1623. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  153. Park, S.; Szumlanski, A.L.; Gu, F.; Guo, F.; Nielsen, E. A role for CSLD3 during cell-wall synthesis in apical plasma membranes of tip-growing root-hair cells. Nat. Cell Biol. 2011, 13, 973–980. [Google Scholar] [CrossRef] [PubMed]
  154. Yang, J.; Bak, G.; Burgin, T.; Barnes, W.J.; Mayes, H.B.; Peña, M.J.; Urbanowicz, B.R.; Nielsen, E. Biochemical and genetic analysis identify CSLD3 as a beta-1,4-glucan synthase that functions during plant cell wall synthesis. Plant Cell 2020, 32, 1749–1767. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  155. Hu, H.; Zhang, R.; Tang, Y.; Peng, C.; Wu, L.; Feng, S.; Chen, P.; Wang, Y.; Du, X.; Peng, L. Cotton CSLD3 restores cell elongation and cell wall integrity mainly by enhancing primary cellulose production in the Arabidopsis cesa6 mutant. Plant Mol. Biol. 2019, 101, 389–401. [Google Scholar] [CrossRef] [PubMed]
  156. Yin, Y.; Johns, M.A.; Cao, H.; Rupani, M. A survey of plant and algal genomes and transcriptomes reveals new insights into the evolution and function of the cellulose synthase superfamily. BMC Genom. 2014, 15, 260. [Google Scholar] [CrossRef] [Green Version]
  157. Si, J.; Zhu, Y. Polygonati Rhizome—A new high-quality crop with great potential and not occupying farmland. Sci. Sin. Vitae. 2021, 51, 1477–1484. [Google Scholar] [CrossRef]
  158. Lowe, N.M. The global challenge of hidden hunger: Perspectives from the field. Proc. Nutr. Soc. 2021, 80, 283–289. [Google Scholar] [CrossRef]
  159. Akhtar, S. Malnutrition in South Asia—A Critical Reappraisal. Crit. Rev. Food Sci. Nutr. 2016, 56, 2320–2330. [Google Scholar] [CrossRef]
  160. Li, X.; Yadav, R.; Siddique, K.H.M. Neglected and underutilized crop species: The key to improving dietary diversity and fighting hunger and malnutrition in Asia and the Pacific. Front. Nutr. 2020, 7, 593711. [Google Scholar] [CrossRef]
  161. Jin, P.; Liang, Z.; Li, H.; Chen, C.; Xue, Y.; Du, Q. Biosynthesis of low-molecular-weight mannan using metabolically engineered Bacillus subtilis 168. Carbohydr. Polym. 2021, 251, 117115. [Google Scholar] [CrossRef]
  162. Zhu, Q.; Zeng, D.; Yu, S.; Cui, C.; Li, J.; Li, H.; Chen, J.; Zhang, R.; Zhao, X.; Chen, L.; et al. From golden rice to aSTARice: Bioengineering astaxanthin biosynthesis in rice endosperm. Mol. Plant 2018, 11, 1440–1448. [Google Scholar] [CrossRef] [PubMed]
Genes 13 01957 g001 550
Figure 1. Epiphytic cultivation model of D. catenatum. (A). Facility-aided cultivation; (B) Rock-dependent eco-cultivation; (C) Trunk-dependent eco-cultivation; (D) Stereo cultivation.
Figure 1. Epiphytic cultivation model of D. catenatum. (A). Facility-aided cultivation; (B) Rock-dependent eco-cultivation; (C) Trunk-dependent eco-cultivation; (D) Stereo cultivation.
Genes 13 01957 g001
Genes 13 01957 g002 550
Figure 2. Compositions of different glucomannans in D. catenatum ([27,29,30]).
Figure 2. Compositions of different glucomannans in D. catenatum ([27,29,30]).
Genes 13 01957 g002
Genes 13 01957 g003 550
Figure 3. The effects of glucomannan from D. catenatum stem. DOP, Dendrobium officinale polysaccharide; TLR4, toll-like receptor4; IL-4, Interleukin-4; IL-6, Interleukin-6; IL-10, Interleukin-10; IL-1β, Interleukin-1β; TNF, tumor necrosis factor; PI3K/AKT, phosphatidylinositol 3 kinase/protein kinase B; CXCR4, chemokine receptor4; CCR7, CC chemokine receptor 7 CC chemokine receptor 7; AMPK, adenosine monophosphate-activated protein kinase; ULK-1, UNC-51 like autophagy activating kinase 1; LC3, light chain 3; SCFAs, short-chain fatty acids; GPRs, g-protein-coupled receptors; MAPK, mitogen-activated protein kinase; PP, Peyer’s patche; MLN, mesenteric lymph node; MNNG, 1-methyl-2-nitro-1-nitroguanidine; GS, glycogen synthase; GP, glycogen phosphorylase; GSK-3β, glycogen synthase kinase 3β; PK, pyruvate kinase; HK, hexokinase; PEPCK, phosphoenolpyruvate carboxykinase; G6Pase, glucose-6-phosphatase; GLP-1, glucagon-like peptide-1.
Figure 3. The effects of glucomannan from D. catenatum stem. DOP, Dendrobium officinale polysaccharide; TLR4, toll-like receptor4; IL-4, Interleukin-4; IL-6, Interleukin-6; IL-10, Interleukin-10; IL-1β, Interleukin-1β; TNF, tumor necrosis factor; PI3K/AKT, phosphatidylinositol 3 kinase/protein kinase B; CXCR4, chemokine receptor4; CCR7, CC chemokine receptor 7 CC chemokine receptor 7; AMPK, adenosine monophosphate-activated protein kinase; ULK-1, UNC-51 like autophagy activating kinase 1; LC3, light chain 3; SCFAs, short-chain fatty acids; GPRs, g-protein-coupled receptors; MAPK, mitogen-activated protein kinase; PP, Peyer’s patche; MLN, mesenteric lymph node; MNNG, 1-methyl-2-nitro-1-nitroguanidine; GS, glycogen synthase; GP, glycogen phosphorylase; GSK-3β, glycogen synthase kinase 3β; PK, pyruvate kinase; HK, hexokinase; PEPCK, phosphoenolpyruvate carboxykinase; G6Pase, glucose-6-phosphatase; GLP-1, glucagon-like peptide-1.
Genes 13 01957 g003
Genes 13 01957 g004 550
Figure 4. Putative glucomannan biosynthetic pathway in D. catenatum (modified from [41,44,45,88] Glc, glucose; Fru, fructose; Fru-6-P, fructose-6-phosphate; Glc-1-P, glucosophosphate-1-P; Glc-6-P, glucosophosphate-6-P; Man, mannose; Man-6-P, mannose-6-phosphate; Man-1-P, mannose-1-phosphate; AsA, ascorbic acid; SUT, sucrose transporter; STP, sugar transporter proteins; SuS, sucrose synthase; INV, invertase; FRK, fructokinase; HXK, hexokinase; PGI, phosphoglucose isomerase; UGP, UDP-Glc pyrophosphorylase; AGP, ADP-Glc pyrophosphorylase; GGP, GDP-Glc pyrophosphorylase; PGM, phosphoglucomutase; GPT, glucose-6-phosphate transporter; BT1, brittle-1 protein, an ADP-Glc transporter; PMI, phosphate mannose isomerase; PMM, phosphomannomutase; GMP, GDP-mannose pyrophosphorylase; GMT, GDP-mannose transporter; CSLA, cellulose-like synthase A; CSLD, cellulose-like synthase D.
Figure 4. Putative glucomannan biosynthetic pathway in D. catenatum (modified from [41,44,45,88] Glc, glucose; Fru, fructose; Fru-6-P, fructose-6-phosphate; Glc-1-P, glucosophosphate-1-P; Glc-6-P, glucosophosphate-6-P; Man, mannose; Man-6-P, mannose-6-phosphate; Man-1-P, mannose-1-phosphate; AsA, ascorbic acid; SUT, sucrose transporter; STP, sugar transporter proteins; SuS, sucrose synthase; INV, invertase; FRK, fructokinase; HXK, hexokinase; PGI, phosphoglucose isomerase; UGP, UDP-Glc pyrophosphorylase; AGP, ADP-Glc pyrophosphorylase; GGP, GDP-Glc pyrophosphorylase; PGM, phosphoglucomutase; GPT, glucose-6-phosphate transporter; BT1, brittle-1 protein, an ADP-Glc transporter; PMI, phosphate mannose isomerase; PMM, phosphomannomutase; GMP, GDP-mannose pyrophosphorylase; GMT, GDP-mannose transporter; CSLA, cellulose-like synthase A; CSLD, cellulose-like synthase D.
Genes 13 01957 g004
Genes 13 01957 g005 550
Figure 5. Expression profile of glucomannan pathway genes in tissues and organs of D. catenatum. The raw RNA-seq reads of different tissues and organs in D. catenatum are derived from the NCBI database (www.ncbi.nlm.nih.gov, accessed on 16 September 2022), including the leaf (SRR4431601), the root (SRR5722140), the green root tip (SRR4431599), the white part of the root (SRR4431598), the stem (SRR4431600), the flower bud (SRR4431603), the sepal (SRR4431597), the labellum (SRR4431602), the pollinia (SRR5722145), and the gynostemium (SRR4431596). A heatmap has been generated via TBtools software [89]. The color scale represents log2 of FPKM expression values; green and red indicate a low and high level of gene expression, respectively.
Figure 5. Expression profile of glucomannan pathway genes in tissues and organs of D. catenatum. The raw RNA-seq reads of different tissues and organs in D. catenatum are derived from the NCBI database (www.ncbi.nlm.nih.gov, accessed on 16 September 2022), including the leaf (SRR4431601), the root (SRR5722140), the green root tip (SRR4431599), the white part of the root (SRR4431598), the stem (SRR4431600), the flower bud (SRR4431603), the sepal (SRR4431597), the labellum (SRR4431602), the pollinia (SRR5722145), and the gynostemium (SRR4431596). A heatmap has been generated via TBtools software [89]. The color scale represents log2 of FPKM expression values; green and red indicate a low and high level of gene expression, respectively.
Genes 13 01957 g005
Genes 13 01957 g006 550
Figure 6. Biofortification strategy of glucomannan based on the in-depth dissection of molecular mechanisms and combined application of new-developed technologies.
Figure 6. Biofortification strategy of glucomannan based on the in-depth dissection of molecular mechanisms and combined application of new-developed technologies.
Genes 13 01957 g006
Table
Table 1. Polysaccharides isolated from D. catenatum: monosaccharide compositions, molecular weights, structure unit/backbone chain, and bioactivities.
Table 1. Polysaccharides isolated from D. catenatum: monosaccharide compositions, molecular weights, structure unit/backbone chain, and bioactivities.
NameMolecular Weights (Mw, kDa)Monosaccharide CompositionsBioactivitiesReferences
DOP24699Man:Glc = 7.64:1.00Unknown[23]
DOP35480Man:Glc = 4.50:1.00Unknown[23]
DOP45408Man:Glc = 3.57:1.00Unknown[23]
DOP-1-A1130Man:Glc = 40.2:8.4Unknown[25]
SDOP1660Man:Glc = 4.9:1.0Unknown[26]
DOPW-1389.98Man:Glc = 10.75:1.00Unknown[29]
DOPW-2374.11Man:Glc = 8.82:1.00Unknown[29]
DOP-1389.98Man:Glc = 5.18:1.00Immunomodulatory activity[27]
DOP-2374.11Man:Glc = 4.78:1.00Immunomodulatory activity[27]
DOP-W3-b15.43Man:Glc = 4.5:1.0Immunomodulatory activity[31]
DOP-I-1730Man:Glc = 5.8:1.0Immunomodulatory activity[32]
DOPa810Man:Glc = 5.6:1.0Immunomodulatory activity[32]
DOPb670Man:Glc = 5.9:1.0Immunomodulatory activity[32]
DOPA-1394Man:Glc = 5.8:1.0Immunomodulatory activity[5]
DOPA-2362Man:Glc = 4.5:1.0Immunomodulatory activity[5]
DWDOP11341Man: Glc = 6.79:1.00Unknown[33]
FWDOP11415Man: Glc = 7.46:1.00Anti-tumor activity[33]
DOPA-1229Man:Glc:Gal = 1.00:0.42:0.27Anti-tumor activity[34]
DOP1-DES298Man:Glc = 2.2:1.0Unknown[35]
DOP2-DES30Man:Glc = 3.7:1.0Unknown[35]
LDOP-191.8Man:Gal:Glc:Gal:Ara = 2.0:1.7:1.3:1.6:0.7Anti-inflammatory activity[30]
DLP-11380Man:Glc = 71.69:22.89Immunomodulatory activity
DCP221Man:Glc:Gal = 69.5:30.2:0.3Immunomodulatory activity[36]
DOP/DOPA/DWDOP/FWDOP/LDOP, Dendrobium officinale polysaccharide; SDOP, single Dendrobium officinale polysaccharide; DOPW, water-soluble Dendrobium officinale polysaccharide fraction; DCP, D. catenatum polysaccharides; Man:Glc, mannose:glucose.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Qi, L.; Shi, Y.; Li, C.; Liu, J.; Chong, S.-L.; Lim, K.-J.; Si, J.; Han, Z.; Chen, D. Glucomannan in Dendrobium catenatum: Bioactivities, Biosynthesis and Perspective. Genes 2022, 13, 1957. https://doi.org/10.3390/genes13111957

AMA Style

Qi L, Shi Y, Li C, Liu J, Chong S-L, Lim K-J, Si J, Han Z, Chen D. Glucomannan in Dendrobium catenatum: Bioactivities, Biosynthesis and Perspective. Genes. 2022; 13(11):1957. https://doi.org/10.3390/genes13111957

Chicago/Turabian Style

Qi, Luyan, Yan Shi, Cong Li, Jingjing Liu, Sun-Li Chong, Kean-Jin Lim, Jinping Si, Zhigang Han, and Donghong Chen. 2022. "Glucomannan in Dendrobium catenatum: Bioactivities, Biosynthesis and Perspective" Genes 13, no. 11: 1957. https://doi.org/10.3390/genes13111957

APA Style

Qi, L., Shi, Y., Li, C., Liu, J., Chong, S. -L., Lim, K. -J., Si, J., Han, Z., & Chen, D. (2022). Glucomannan in Dendrobium catenatum: Bioactivities, Biosynthesis and Perspective. Genes, 13(11), 1957. https://doi.org/10.3390/genes13111957

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop