Search Results (153)

Corky split vein (CSV) is a common physiological disease in citrus that can result from multiple types of stresses. Preliminary field investigation found that more severe CSV in citrus cultivated in orchards lacking both boron (B) and other photosynthesis-related nutrients, including manganese (Mn). In this study, two-year-old ‘Newhall’ navel orange seedlings were treated with control (CK), B deficiency (BD), Mn deficiency (MnD), and combined B and Mn deficiency (BD + MnD). After 31 weeks, typical CSV symptoms appeared on old leaves (OLs) and secondary new leaves (SLs) in BD, while BD + MnD symptoms were more severe. BD and BD + MnD significantly reduced B concentrations in all leaf types, but there were no significant differences between them. Except for OLs in MnD, the net photosynthetic rate (P_n) of all leaf types significantly decreased in all treatments, with BD + MnD showing significantly lower P_n values than BD. Compared with BD, BD + MnD significantly increased minimal fluorescence (F_o) of all leaves at the later stage and significantly decreased Y(II) of new leaves. BD significantly increased sucrose and starch contents in all type leaves, while the OL starch content was significantly higher in BD + MnD than that in BD. BD + MnD significantly decreased the enzyme activities of Rubisco, TK, and FBA in OLs, FBPase and NI in PLs, and Rubisco in SLs compared with BD, while the activities of NI and AI in OLs and SS in SLs were significantly increased. BD + MnD significantly enhanced lignin concentrations and the expression of key lignin synthesis genes in leaves compared with BD. In conclusion, Mn deficiency exacerbates B-deficiency-induced CSV not only by intensifying photosynthetic dysfunction and carbohydrate accumulation but also by promoting lignin biosynthesis. These findings highlight the synergistic nature of B and Mn deficiencies in impairing leaf function and structure, providing new insights into the physiological and molecular mechanisms underlying CSV development. Full article

Plant sucrose transporters (SUTs) are essential membrane proteins that mediate sucrose phloem loading in source tissues and unloading in sink tissues. In addition to their role in carbohydrate partitioning, SUTs have been implicated in plant responses to both biotic and abiotic stresses. Our previous research demonstrated that silencing StSUT2 in potatoes (Solanum tuberosum) affects plant growth, flowering time, and tuber yield, with transcriptomic analysis suggesting its involvement in cell wall metabolic pathways. In this study, we further investigated the effects of StSUT2 inhibition on the cell wall structure and biotic stress response of potatoes. Transmission electron microscopy revealed that the tuber cell wall thickness of the StSUT2 RNA interference (RNAi) line RNAi-2 was reduced by 7.8%, and the intercellular space was increased by 214% compared with the wild-type plants. Biochemical analyses showed that StSUT2 silencing significantly decreased cellulose, hemicellulose, and lignin contents in both the leaves and tubers, e.g., tuber cellulose reduced by up to 20.1%, while pectin levels remained unaffected, with distinct effects on source leaves and sink tubers’ organs. Additionally, activities of cellulase, xyloglucan glycosyltransferase/hydrolase XTH, and polygalacturonase were elevated in RNAi lines, e.g., leaf cellulase increased by 43.3%, whereas the pectinase activity was unchanged. Pathogen inoculation assays demonstrated that StSUT2 RNAi lines were more susceptible to Ralstonia solanacearum bacterial wilt and Fusarium sulphureum dry rot, showing larger leaf lesions, wider tuber necrotic plaques, and severe seedling wilting. These findings demonstrate that silencing StSUT2 regulates the cell wall structure, composition, and the activity of cell wall-degrading enzymes, thereby reducing the plant’s resistance to fungal and bacterial pathogens. Full article

This study aims to investigate the effects of selenium (Se) fortification on growth performance and the Se content in kale using Se fertilizer, and it determines the influences of Se fortification on the metabolic profile of kale using quasi-targeted metabolomics. The results showed that Se fortification increased the plant height and leaf weight of kale, up-regulated the total Se content and decreased the chlorophyll and total phenolic contents in kale leaf. Se fortification elevated selenate (Se(IV)), selenite (Se(VI)), selenocystine (SeCys₂), Se-methylselenocysteine (Se-MeSeCys) and selenomethionine (SeMet) contents, as well as total contents of Se in different forms in kale leaf. Se fortification also changed the metabolic profile of kale leaf, via six particular types of compounds (amino acid and its derivatives; organic acid and its derivatives; carbohydrates and its derivatives; lipids; flavonoids; organoheterocyclic compounds) and eight metabolic pathways (alanine, aspartate and glutamate metabolism; amino sugar and nucleotide sugar metabolism; sulfur metabolism; starch and sucrose metabolism; taurine and hypotaurine metabolism; glycolysis/gluconeogenesis; fructose and mannose metabolism; nitrogen metabolism). Moreover, 24 metabolic biomarkers were screened for kale leaf affected by Se fortification. Furthermore, correlations were observed between metabolic biomarkers and Se contents as well as speciation. These results indicate that Se fortification has a significant influence on the growth performance and nutritional compounds of kale, providing references for the future study on the production and bioactivity of Se-enriched kale. Full article

Foliar fertilizers are efficient in enhancing nutrient utilization. This experiment aims to improve leaf physiological functions, enhance fruit quality, increase yield, and boost orchard productivity through the screening of foliar fertilizers suitable for apple trees. The 6-year-old apple trees of the ‘Snick’ were used as experiment material. The results of measurements amino acids, calcium, boron, and potassium indicate that different foliar fertilizers can improve fruit quality and aroma by enhancing leaf physiological functions. In apple fruit, amino acid foliar fertilizer increased the tartaric acid content by 44.26%. Calcium foliar fertilizer resulted in a 32.39% increase in vitamin C, a 19.71% increase in sucrose compared to the control, with a total aroma substance increase of 13.41%. Boron foliar fertilizer elevated flavonoid content in the peel to 3.67 mg·g⁻¹, a 70.69% increase over the CK. Potassium foliar fertilizer significantly improved fruit appearance, phenolic substances in the peel, soluble protein content by 25.39%, and glucose content by 55.91%. Therefore, mineral source fulvic acid potassium foliar fertilizer was demonstrated the best overall effect, effectively enhancing fruit quality and flavor. These results provide a theoretical basis and scientific reference for improving apple quality. Full article

Background: Dietary polyphenols, particularly flavonoids, have been associated with improved glycemic control and reduced risk of type 2 diabetes. Raspberry leaf (RL) is a rich but underexplored source of such bioactives, including ellagitannins, flavonoids, and phenolic acids. While raspberry fruit has received some attention in nutritional science, the metabolic effects of raspberry leaf—especially its influence on postprandial glucose and insulin responses—remain largely unstudied. Objective: This study is the first to investigate the acute effects of RL tea consumption on postprandial blood glucose and insulin levels in healthy individuals following intake of common dietary carbohydrates (sucrose and glucose). Methods: In a randomized crossover study, 22 healthy adults (12 males, 10 females) consumed 50 g of glucose or sucrose with or without 10 g of RL tea in four separate sessions. Blood glucose and insulin levels were measured at fasting and at 15, 30, 60, 90, and 120 min post-ingestion. A total of 37 polyphenolic compounds were identified in the RL infusion using LC–MS, following a 5-minute hot water extraction. The contents of ellagitannins, flavonoids, and phenolic acids were 38 mg, 7 mg, and 4 mg per 10 g of RL, respectively, contributing to a total polyphenol content of 50 mg per 10 g. Results: When RL tea was consumed with sucrose, postprandial blood glucose levels were significantly reduced at 15 and 30 min by 1.19 ± 0.88 mmol/L (25.59% reduction, p = 0.001) and 2.03 ± 1.05 mmol/L (43.57% reduction, p = 0.0004), respectively. Insulin concentrations were also significantly lower at 15 min (113.90 ± 59.58 pmol/L, p = 0.019), 30 min (161.76 ± 91.96 pmol/L, p = 0.0008), and 60 min (139.44 ± 75.96 pmol/L, p = 0.025). No significant differences were observed with glucose ingestion. Conclusions: This study provides the first clinical evidence that RL tea can blunt early postprandial glycemic and insulinemic responses to sucrose in healthy individuals. The data suggest that these effects are likely mediated by relatively low levels of polyphenols—particularly ellagic acid—through inhibition of carbohydrate-digesting enzymes such as α-glucosidase and β-fructofuranosidase. These findings support the potential of RL tea as a simple, dietary approach to modulate glucose metabolism and warrant further investigation in populations at risk for metabolic disorders. Full article

Constrained by site conditions and water resources, pear tree cultivation faces increasing drought stress. Paecilomyces variotii extract (PVE), a novel biostimulant extracted from wild sea buckthorn root-isolated strains and containing chitin, humic/fulvic acids, and beneficial microbes, has gained attention due to its high activity and efficacy in alleviating plant stresses (e.g., drought). In this study, Pyrus pyrifolia ‘Qiu Yue’ was used as the experimental material, and pot experiments were conducted to examine the drought-mitigating effects of different PVE concentrations. Drought stress was achieved by maintaining soil water content at 35–45% of water holding capacity for 45 days under natural evaporation conditions in rain shelters. The growth status of pear trees, soil enzyme activity, and metabolite levels were analyzed. The results showed that the application of 5 ng/mL PVE promoted pear tree growth, enhanced leaf antioxidant enzyme activity, and improved photosynthetic capacity and soil enzyme activity. Under normal water conditions, the shoot growth length, plant height, stem diameter, and root system activity of the 5 ng/mL PVE group were 31.91%, 12.05%, 3.54%, and 10.94% higher than those of the control group, respectively. Under drought stress, these values increased by 25.12%, 8.87%, 12.21%, and 16.98%, respectively. The addition of 5 ng/mL PVE facilitates trehalose release and upregulates starch-sucrose, glycerophospholipid, and galactose metabolic pathways, thereby potentiating drought stress tolerance in pear trees. However, at 20 ng/mL, reductions were observed in pear tree growth indicators, leaf antioxidant enzyme activity, soil enzyme activity, and trehalose content in root exudates compared to the 5 ng/mL PVE treatment. Overall, 5 ng/mL PVE effectively promotes pear tree growth and enhances drought resistance, making it suitable for broader use in pear cultivation practices. Full article

Mycorrhizal symbiosis relies on the host’s supply of carbohydrates, while sugar transport within plants is governed by the SWEET sugar transporter family. Although the symbiotic association between arbuscular mycorrhizal fungi (AMF) and maize is critical for its growth and sugar regulation, different AMF species have varying impacts on the host. The aim of this study was to analyze the effects of inoculating six different AMF species [Diversispora epigaea (De), Rhizophagus intraradices (Ri), Paraglomus occultum (Po), Entrophospora etunicata (Ee), Glomus heterosporum (Gh), and Funneliformis mosseae (Fm)] on plant growth, leaf photosynthetic capacity, glomalin-related soil protein content, leaf sugar content, and SWEET gene expression of maize under potted conditions for two months. AMF species colonize maize roots and showed significant species-specific variation, where Ri and Fm colonized treatment had the greatest rates (66~68%). All six fungi significantly increased biomass and stem diameter, with Ee treatment yielding the thickest stems, and enhanced leaf photosynthetic performance and glomalin-related soil protein fractions to some extent, with species-specific enhancements. All AMF species in particular significantly increased leaf sucrose; all except Ri treatment significantly increased fructose; while only Po and Fm treatments significantly increased glucose. AMF inoculations consistently upregulated the expression of ZmSWEET1b/3a/3b/4a/4b/14a and 16 genes, consistently downregulated the expression of ZmSWEET6b/11b/12a/13a/13b/13c and 17b genes, and induced treatment-specific regulation in the other gene expression. Root AMF colonization clustered with sugars and specific ZmSWEETs, with ZmSWEET4a/15b and 14b central to sucrose/glucose based on principal component analysis, indicating that these genes have specific regulatory effects in response to AMF treatments. In short, AMF inoculation reprogrammed ZmSWEET expression in a species-specific manner, with core ZmSWEET genes mediating sugar accumulation to support symbiosis. Full article

Improving yield stability under water-limited conditions is a key objective of wheat breeding programmes. One trait of particular interest is carbohydrate accumulation and remobilisation. This study assessed the genetic basis of aspects of yield and flag leaf sugar contents under drought and well-watered conditions using QTL mapping in a population of 90 doubled haploid lines derived from the cross Chinese Spring × SQ1. As well as soluble sugar content, glucose, fructose, sucrose, and maltose, the traits grain yield (Yld), biomass (Bio), and thousand grain weight (TGW) were also analysed. Analysis of variance showed that genotype, environment and their interactions significantly influenced all the traits studied, with environmental effects explaining up to 74.4% of the total variation. QTL analysis identified 40 QTLs for Yld, TGW, and Bio as well as 53 QTLs for soluble carbohydrates, accounting for up to 40% of phenotypic variation. QTLs coincident for more than one trait were identified on 21 chromosome regions, associated with carbohydrate metabolism and yield performance under drought, particularly on chromosomes 2D, 4A, 4B, 5B, 5D, 6B, and 7A. Candidate genes for several yield-related QTLs were identified. These results provide useful genetic markers for the development of more drought-resistant wheat cultivars. Full article

Straw returning inhibits tillering at the early stage of rice growth and thus affects grain yield. Sulfur-coated urea (SCU) has been expected to increase nitrogen use efficiency (NUE) and yield, save labor input, and reduce environmental pollution in crop production. Nevertheless, the sulfur coatings of SCU are easy to break and then shorten the nutrient release cycle. Whether there was a complementary effect between straw returning and SCU in NUE and grain yield had remained elusive. To investigate the effects of straw returning combined with the application of SCU on NUE and rice yield, a two-year field experiment was conducted from 2022 to 2023 with three treatments (straw returning combined with conventional urea (SRU), no straw returning combined with SCU (NRS), straw returning combined with SCU (SRS)). We found that straw returning combined with the application of SCU increased rice yield and NUE significantly. Compared with SRU and NRS, SRS treatments significantly increased grain yield by 14.61–16.22%, and 4.14–7.35%, respectively. Higher effective panicle numbers per m² and grain numbers per panicle were recorded in NRS and SRS treatments than SRU. SRS treatment increased nitrogen recovery efficiency by 79.53% and 22.97%, nitrogen agronomic efficiency by 18.68% and 17.37%, and nitrogen partial factor productivity by 10.51% and 9.81% compared with SRU and NRS treatment, respectively. The enhanced NUE in SRS was driven by higher leaf area index, SPAD value, net photosynthetic rate, carbon metabolic enzyme (RuBP and SPS) activity, nitrogen metabolic enzyme (NR, GS, and GOGAT) activity, sucrose and nitrogen content in leaves, and nitrogen accumulation in plant during grain filling. Moreover, the improved yield in SRS was closely related to superior NUE. In conclusion, straw returning combined with application of SCU boosted grain yield and NUE via enhanced carbon–nitrogen metabolism during the late growth period in rice. Full article

Qingke (Hordeum vulgare L. var. nudum Hook. f.), a staple crop in the Tibetan Plateau, suffers from severe yield reduction under continuous cropping (by 38.67%), yet the underlying mechanisms remain unclear. This study systematically investigated the effects of 23-year continuous cropping (23y-CC) on the nutrient dynamics, carbohydrate metabolism, and enzymatic activities in Qingke leaves across five developmental stages (T1: seedling; T2: tillering; T3: jointing; T4: flowering; T5: filling). Compared to the control (first-year planting), 23y-CC significantly reduced leaf nitrogen (N), phosphorus (P), and potassium (K) contents by 60.94%, 47.96%, and 60.82%, respectively, at early growth stages. Key nitrogen-metabolizing enzymes, including glutamate synthase (GOGAT), glutamine synthase (GS), and nitrate reductase (NR), exhibited reduced activities under 23y-CC, indicating impaired nitrogen assimilation. Carbohydrate profiling revealed lower starch and glucose contents but higher sucrose accumulation in later stages (T4–T5) under 23y-CC, accompanied by the dysregulation of sucrose synthase (SS) and invertase activities. These findings elucidate how continuous cropping disrupts nutrient homeostasis and carbon allocation, ultimately compromising Qingke productivity. This study provides novel insights into agronomic strategies for mitigating continuous cropping obstacles in Qingke. Full article

Environmental and health concerns have increased the demand for ready-to-eat vegetables rich in bioactive compounds. This study explores the impact of red and blue (R:B) LED light on the metabolic responses of lamb’s lettuce (Valerianella locusta L.), focusing on sugars, organic acids, total phenolics, antioxidant activity, and enzyme inhibition. Post-harvest analyses were also conducted to assess shelf-life and microbiological characteristics of the product. The R:B LED treatment significantly enhanced plant growth, with a 133% and 68% increase in shoot fresh and dry weights, respectively, and a 21% increase in leaf area compared to controls (white LED light). Biochemical profiling revealed substantial increases in fructose (255%), sucrose (169%), citric acid (350%), and malic acid (868%) under R:B LED light. Additionally, phenolic content increased by 30%, alongside a notable modulation of 258 secondary metabolites, including flavonoid glycosides, alkaloids, and terpenoids. These biochemical changes contributed to a marked improvement in antioxidant capacity (12–45% across multiple assays) and a 300% increase in α-glucosidase inhibition, suggesting potential antidiabetic properties. Furthermore, post-harvest analysis revealed comparable shelf-life and microbiological safety between R:B and white LED-grown samples. The research highlights the potential of LED light to enhance plant biochemical responses and improve crop quality without affecting post-harvest quality, paving the way for sustainable agricultural innovations. Full article

Banana plants require substantial nutrients, and their growth is significantly hindered by nutrient deficiency. This study investigated the influences of Piriformospora indica colonization on the growth of clean river sand-cultivated banana plants under varying phosphorus (P) and potassium (K) levels. Banana plants without (CK) and with P. indica colonization (PI) were watered using Hoagland solutions with four gradients of P or K (100%, 50%, 25%, and 0%). Results showed that P. indica colonization promoted the growth of banana plants under different concentrations of P and K treatments. Further analysis revealed that the pseudo-stem P and K contents were very significantly (p < 0.01) positively and positively correlated with biomass-related parameters (aboveground part fresh weight, root fresh weight, and total plant biomass), respectively. Root starch, sucrose, proline (PRO), and anthocyanins contents, as well as leaf malondialdehyde (MDA) and PRO contents, were positively correlated with most growth-related parameters. However, root and leaf flavonoid contents, total antioxidant capacity (T-AOC), and leaf anthocyanin content showed negative correlations with growth-related parameters. Moreover, a very significant negative correlation (p < 0.01) was identified between root T-AOC and root starch content. Additionally, P. indica altered the P and K reduction-caused starch content change patterns in both leaves and roots. Our study demonstrated that P. indica colonization promoted the growth of banana under different concentrations of P and K treatments by mediating the accumulation of carbohydrates, secondary metabolites, osmoprotectants, and so on. Full article

According to previous studies, dynamic light regimes might enhance seedling development, survival rates, or economic efficiency in factory-based seedling production systems compared to continuous red and blue light irradiation. However, there have been few studies revealing the effects of discontinuous red and blue light on the carbohydrate accumulation and metabolism of tomato seedlings. Therefore, we planted tomato seedlings in an artificial light plant factory under a red background light with intermittent blue light intervention, namely R (as the control), R/RB₃₂, R/RB₄₀, R/RB₆₄, and R/RB₈₀ at an equal daily light integral. The growth, carbohydrate accumulation, and sugar metabolism were analyzed to investigate the effects of dynamic lighting modes on tomato seedlings. The results demonstrated the following: (1) Pure red light induced spindling of tomato seedlings, while intermittent blue light treatments enhanced stem thickness, leaf number, and leaf area, resulting in greater biomass accumulation. Among these treatments, the highest antioxidant enzyme activity and the lowest reactive oxygen species (ROS) content, accompanied by the highest biomass, were all observed in tomato seedlings subjected to R/RB₈₀ (intermittent supplementation of 80 μmol·m⁻²·s⁻¹ blue light under red light background). (2) The carbohydrate accumulation in tomato seedlings was increased under all treatments relative to the control. The sucrose content, enzyme activity, and gene expression level of sucrose phosphate synthase (SPS) were all up-regulated in tomato leaves treated with blue light irradiation compared with pure R. In addition, the highest soluble sugar content, along with the peak SPS activity and gene expression, was observed under the R/RB₈₀ treatment. Meanwhile, the lowest fructose content accompanied by the lowest activity and gene expression of sucrose synthase (SS) were observed in tomato leaves treated with R/RB₃₂. This implies that blue light supplementation may regulate sugar accumulation by modulating the activity or expression of enzymes involved in sucrose metabolism. (3) Moreover, shoot biomass, enzyme activity, and expression level of SPS were all found to increase with the increase in supplementary blue light intensity, indicating that short-duration high-intensity blue light was more effective in promoting carbohydrate accumulation in tomato seedlings than long-term low-intensity blue light based on the equal DLI. Full article

Sugar beet is a nitrogen (N)-sensitive crop, and its N regulation and utilization are critical for enhancing productivity. Sugar beet seedlings at the two-true-leaf-pair stage were hydroponically grown in an artificial climate chamber. Leaves and roots from three seedlings per treatment were sampled at 10, 20, 25, and 30 days after exposure to N treatments (N5: 5 mmol/L, N10: 10 mmol/L, N15: 15 mmol/L, and N20: 20 mmol/L) to assess the effects of N supply level on growth, photosynthesis, and carbon and nitrogen metabolism. The results revealed a time-dependent dynamics in beet biomass accumulation, with N20 inducing chlorosis and necrosis symptoms by 10 days post-treatment (DPT), resulting in the lowest biomass. While N15 significantly promoted root biomass by 30 DPT, showing a 23.70% (root dry weight, RDW) increase over N20; chlorophyll content and gas exchange parameters-net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) exhibited significant N dependence, with N15 maintaining high chlorophyll level (0.78 mg/g) and photosynthetic rate (220.33 μmol/(m²·s). Nitrogen assimilation, as indicated by glutamine synthetase and glutamate synthetase activity (GS and GOGAT), was stronger under N15, promoting amino acid synthesis and root growth, whereas N20 inhibited enzyme activity. Carbon metabolism analysis revealed that N15-driven sucrose synthesis significantly increased root sucrose content, sucrose phosphate synthase and sucrose synthase activity (SPS and SS), optimizing source–sink allocation. Correlation analysis showed a positive relationship between leaf and root biomass (r = 0.91), and root sucrose content was positively correlated with GOGAT activity (r = 0.90), emphasizing the synergistic regulation of C/N metabolism. On the contrary, N20 led to disrupted C/N metabolic homeostasis, inhibited enzyme activity, and C/N distribution. These results indicated that the photosynthetic output, enzyme efficiency, and sucrose distribution were coordinated by nitrogen optimization, and the growth of sugar beet seedlings was optimized. Full article

Cotton root systems sustain photosynthesis by nutrient uptake and coordinate with above-ground growth to influence yield. This study explored the effects of fulvic acid (FA) and phosphorus (P) fertilizers on the relationships between cotton photosynthetic capacity (CAP) and root carbohydrate metabolism. A field experiment was conducted including five treatments: no P fertilizer (CK), 105 kg P₂O₅ ha⁻¹ (P1), 150 kg P₂O₅ ha⁻¹ (P2), 105 kg P₂O₅ ha⁻¹ + FA (FP1), and 150 kg P₂O₅ ha⁻¹ + FA (FP2). Results found that FP2 showed the most significant advantage, ensuring a suitable leaf area index (LAI) and cotton fractional interception of photosynthetically active radiation (IPAR) and consequently maintaining a high CAP. Compared with FP2, FP1 resulted in an increase in the boll loading of the root system (BLR) by 8.1% and the boll capacity of the root system (BCR) by 9.3%. From the peak flowering stage to the peak boll setting stage, sucrose and starch contents in FP1 were 6.2–19.2% and 26.5–27.9% lower than those in FP2, respectively. Conversely, fructose and glucose contents in FP1 were 6.4–10.8% and 7.2–8.8% higher than in FP2. The cotton reproductive organ biomass was increased by 11.1% and 14.7% relative to FP2. Moreover, FP1 achieved the highest yield, with an increase of 8.5% and 11.0% compared with P2 and FP2, respectively. Taken together, our study suggests that application of FP1 (105 kg P₂O₅ ha⁻¹ + FA) could be a proper P fertilization method in cotton production of saline-alkali and arid regions. Full article