Search Results (41)

Dioscorea species, known as “Yams”, belong to the Dioscoreaceae family. Members of the Dioscoreaceae family are widely distributed across subtropical and tropical regions. They are notable for their high content of starch, dietary fiber, and various bioactive compounds. In addition to serving as a staple food source, these tubers possess significant medicinal value in traditional medicine, particularly for treating diabetes, diarrhea, and various inflammatory diseases. This study aimed to comprehensively summarize the active components and food development potential of Dioscorea species from research over the past decade by searching commonly used databases such as PubMed, Web of Science, Scopus, and Google Scholar. This review highlights the classification of bioactive compounds in Dioscorea spp. using the NPClassifier tool. We discuss 60 representative bioactive metabolites, including terpenoids, phenylpropanoids, carbohydrates, fatty acids, alkaloids, and amino acids. Additionally, we discuss the functional food applications and regulations of Dioscorea spp., which possess antioxidant, anti-inflammatory, anti-diabetic, and anticancer properties. This review is expected to provide scientific ideas for future research related to prioritizing the optimization of extraction technologies, the execution of rigorous clinical trials to confirm therapeutic effects, and the exploration of novel applications of Dioscorea spp. bioactives to fully harness their potential in improving human health. Full article

This study evaluated the therapeutic potential of 70% ethanol extracts from six medicinal plants (Chenopodium album, Cassia tora, Cudrania tricuspidata, Dioscorea polystachya, Lonicera japonica, Solidago virgaurea subsp. gigantea) through their antibacterial, antioxidant, cytotoxic, and immunomodulatory activities, targeting applications in aquaculture. All extracts exhibited potent antibacterial activity (MIC ≤ 10 μg/mL) against Aeromonas spp. and Photobacterium damselae subsp. damselae, but limited efficacy against Streptococcus parauberis. C. tricuspidata (CTR) and C. tora (CTO) demonstrated superior antioxidant activity (IC₅₀ = 1292 μg/mL and IC₅₀ = 227 μg/mL, respectively), correlating with high polyphenol content (1498 and 1409 mg GAE/g). CTR displayed significant concentration-dependent cytotoxicity (IC₅₀ = 904.2 μg/mL), while C. album (CA) promoted cell proliferation (132.3% viability). In LPS-stimulated CHSE-214 cells, D. polystachya (DP) induced the highest IL-8 expression (207-fold), followed by Chenopodium album (CA) (194-fold IL-8, 49-fold TNF-α) and CTR (245-fold RIPK2), activating NF-κB, MAPK, and NOD-like receptor pathways critical for teleost immunity. Lonicera japonica (LJ) suppressed TNF-α (0.4-fold) and IRF1 (0.3-fold), indicating anti-inflammatory potential, while S. virgaurea subsp. gigantea (SV) showed biphasic TNF-α modulation (79-fold at 10 μg/mL, 5-fold at 100 μg/mL). These diverse bioactivities, particularly the robust immunomodulatory effects, highlight the promise of these extracts as natural therapeutic agents for fish health management in aquaculture. Full article

Yam (Dioscorea spp.) provides various nutritional and medicinal benefits, including a high starch content, dietary fiber, essential micronutrients, and bioactive compounds. The molecular mechanisms underlying tuber expansion have not yet been clarified. Rapid alkalinization factor (RALF) genes, which mediate various processes in plants, are thought to contribute to the regulation of tuber growth; however, their role in yam development, especially in gibberellin (GA)-mediated processes, remains unclear. Here, we characterized seven DrRALF genes in the yam genome. Analysis of gene duplication demonstrated that the expansion of DrRALF genes was primarily driven by whole-genome duplication or segmental duplication. Phylogenetic analysis revealed that DrRALF genes were concentrated in specific clusters, indicating that their functions are relatively conserved. DrRALF5 was specifically expressed in the roots, and DrRALF2, DrRALF3, DrRALF4, and DrRALF6 were highly expressed in flowers. DrRALF1, DrRALF2, DrRALF3, DrRALF4, DrRALF5, and DrRALF6 were shown to play a role in tuber expansion. Subsequent qRT-PCR validation of four selected DrRALF genes confirmed the regulation of DrRALF2, DrRALF4, DrRALF5, and DrRALF6 by GA and PP333 (paclobutrazol, a GA biosynthesis inhibitor). Yeast one-hybrid assays further showed that the DrRALF6 promoter region interacted with the GA-signaling protein, DrDELLA1. Our findings provide novel insights into the regulatory network controlling yam tuber expansion, especially through the interaction between DrRALF6 and GA signaling pathways. Our results clarify the molecular mechanisms involved in tuber growth and propose a promising strategy for improving yam production through genetic manipulation of the GA-RALF signaling pathway. Full article

Yam (Dioscorea spp.) has been a prominent food and cash crop for most farmers in the yam production areas of Ghana, with the sales of yam in both domestic and international markets contributing significantly to the economy of the country. However, yam production by smallholder farmers is constrained by several challenges, including postharvest loss resulting from yam nematodes. This study conducted field surveys across seven districts across Ghana to collect data from randomly selected 150 yam farmers to investigate the status of nematode infestation, management practices and other socio-economic factors contributing to yam production in the country. The most common farm size for yam production from 2019 to 2022 was between 0.4 and 0.8 hectares. The majority of the farmers (56%) have been farming for over 15 years, with 6–10 years of experience in yam production, and preferred to use their own planting materials every year. Although most farmers (97.99%) experienced pests and diseases, most of them (77.33%) had no knowledge about nematode infestations in their farm causing damage to the tubers. Although yam farmers experienced yield losses, farmers were unable to manage nematode infestations in their farms. Twelve (12) genera of nematodes were identified in soils of yam rhizosphere across the seven districts. Tylenchus spp. (35.5%) and Scutellonema spp. (92.8%) were the most abundant nematode in soil samples and tuber peels, respectively while the second highest nematode in tuber peels was Meloidogyne spp. (4.0%). The presence of these parasitic nematodes in yam farms across Ghana suggests serious threats to the growth and yield of yams, although their presence is either not known or is usually neglected. Our result also confirmed the correlation between farmer storage practices and the management of nematodes, suggesting some storage practices such as barns may be effective in controlling nematodes. On the other hand, we find no association between pest occurrence in the field and nematode management. The lack of an association could be an indication that pest management in the field and nematode management in storage are separate activities and this underlines the importance of providing tailored postharvest training for smallholder farmers in effectively managing nematodes. It was therefore necessary to undertake this study and establish knowledge on the species as well as their prevalence in the farms across Ghana, contributing towards enhanced farmers’ understanding on nematode management and effective storage of yams to prevent losses caused by nematode infestation. Full article

Potyvirus diseases are one of the main challenges facing the production of yam (Dioscorea spp.). The objective of this study was to identify the potyviruses present in the Dioscorea spp. germplasm collection at Instituto de Investigaciones de Viandas Tropicales (INIVIT) to establish methodologies for the characterization of the associated diseases. For this purpose, immunochemical and molecular methods were used to identify the potyviruses present. The symptomatology of Dioscorea spp. at INIVIT’s germplasm collection was described. In addition, the severity and incidence in the germplasm collection and production areas were evaluated. As a result, the first report of yam mosaic virus (Potyvirus yamtesselati) and yam mild mosaic virus (Potyvirus yamplacidum) in Cuba is presented. The existence of resistant, tolerant, and susceptible cultivars to potyvirus-associated diseases in the germplasm collection was detected, and the incidence of these diseases was higher than 64% in the production areas evaluated. This study represents a step forward in the establishment of certification programs for propagating material of Dioscorea spp. in Cuba. Full article

Yam (Dioscorea spp.) is a main staple tuber crop in Nigeria and the West African region. Its performance is determined by genotypes and also the environment of growth. This study assessed the agronomic performance and yield stability of elite white yam (Dioscorea rotundata) genotypes across diverse Nigerian environments. A total of 25 genotypes were evaluated at three locations in two consecutive growing seasons, 2022 and 2023, for fresh tuber yield, disease resistance, and tuber quality traits. The genotype’s performance and stability for the measured traits were assessed using various analytical tools such as additive main effects and multiplicative interaction (AMMI) and multi-trait stability index (MTSI). The AMMI analysis revealed significant differences among the genotypes and across the environments for all traits (p < 0.001, p < 0.01). The PCA revealed that the first two principal components (PC1 and PC2) explained a substantial portion of the total variation (49.84%). The MTSI identified four clones: G18, G19, G24, and G16 as promising candidates for improved yam production in Nigeria with high and stable performance for the multiple traits. Full article

Yam (Dioscorea spp.) is an important tuber crop consumed globally. However, stable yam production faces challenges from a variety of diseases caused by fungi, nematodes, viruses, and bacteria. Prominent diseases such as anthracnose, leaf spot, yam wilt, dry rot, and crazy root syndrome, currently pose serious threats to yam yields. These diseases not only result in quality degradation but also cause great economic losses. This review summarizes the damages, symptoms, causal agents, and epidemic factors of major yam diseases. It also outlines a comprehensive disease control strategy that includes the use of resistant varieties, proper crop rotation, sanitation measures, and the application of agrochemicals and biocontrol agents. Additionally, this review addresses future perspectives on risk factors and knowledge gaps, aiming to serve as a reference for in-depth research into advanced disease monitoring and control technologies for yams. Full article

Phenotyping yam (Dioscorea spp.) germplasm for resistance to parasitic nematodes is hampered by the lack of an efficient screening method. In this study, we developed a new method using rooted yam vine cuttings and yam plantlets generated from semi-autotrophic hydroponics (SAHs) propagation for phenotyping yam genotypes for nematode resistance. The method was evaluated using 26 genotypes of D. rotundata for their reaction to Scutellonema bradys and four root-knot nematode species, Meloidogyne arenaria, M. enterolobii, M. incognita, and M. javanica. Yam plantlets established in nursery bags filled with steam-sterilized soil were used for screening against single nematode species. Plants were inoculated four weeks after planting and assessed for nematode damage eight weeks later. A severity rating scale was used to classify genotypes as resistant, tolerant, or susceptible determine based on the nematode feeding damage on tubers and the rate of nematode multiplication in the roots of inoculated plants. The results demonstrated putative resistance and tolerance against S. bradys in 58% of the genotypes and 88%, 65%, 65%, and 58% against M. arenaria, M. javanica, M. incognita, and M. enterolobii, respectively. The method is rapid, flexible, and seasonally independent, permitting year-round screening under controlled conditions. This method increases the throughput and speed of phenotyping and improves the selection process. Full article

Background: Dalmatian Zagora has experienced significant depopulation trends over recent decades. The area is very interesting because of its rich biodiversity of species as well as its history of the use of wild foods. Since there is a danger of permanent loss of knowledge on the use of wild edibles, we focused our research on recording traditions local to this area. Methods: We conducted interviews with 180 residents. Results: A record was made of 136 species of wild food plants and 22 species of edible mushrooms gathered in the area. The most frequently collected species are Rubus ulmifolius Schott, Cornus mas L., Portulaca oleracea L., Asparagus acutifolius L., Sonchus spp., Morus spp., Taraxacum spp., Amaranthus retroflexus L., Cichorium intybus L., and Dioscorea communis (L.) Caddick & Wilkin. Conclusions: The list of taxa used is typical for other (sub-)Mediterranean parts of Croatia; however, more fungi species are used. The most important finding of the paper is probably the recording of Legousia speculum-veneris (L.) Chaix, a wild vegetable used in the area. Full article

Dioscorea spp. is known for its myriad medicinal properties. D. alata, specifically crude extracts, have displayed potent anticancer properties. However, the chemical constituents of these extracts have not been examined. The aim of this study is to determine the chemical composition and antioxidant characteristics of the active extracts from D. alata tuber. Chemoinformatic profiling of the Jamaican Dioscorea alata cultivar white yam tuber was generated by a sequential Soxhlet extraction of dried milled tuber, producing five crude extracts: hexane (E-1), diethyl ether (E-2), acetone (E-3), ethanol (E-4) and water (E-5). The analytes within the five extracts were dissolved in 0.1% DMSO and their anticancer activity was determined using DU145 prostate cancer cells. Both the acetone and the ethanolic extract were able to induce greater than 50% cell death at 50 µg/mL. The order of growth inhibition of the extracts in DU-145 cell is E3 (IC₅₀, 10.81 µg/mL) > E-4 (IC₅₀ 24.17 µg/mL) > E-1 (IC₅₀ > 100 µg/mL) ≥ E-2 (IC₅₀ > 100 µg/mL) ≥ E-5 (IC₅₀ > 100 µg/mL). Phytochemical screening of both E-3 and E-4 revealed the presence of all major classes of secondary metabolites except tannins. Resins were also absent in the E-3 extract. Phenolic quantification indicated that E-3 and E-4 possessed GAEs of 31 ± 1.1 and 72 ± 1.8 mg per g of sample, respectively. Inversely, E-3 displayed greater antioxidant capability with IC₅₀ of 82.9 µg/mL compared to E-4 (166.9 µg/mL); however, neither was comparable to citric acid (33.6 µg/mL). The extract E-3 was further isolated by HPLC into 11 fractions. Fractions 4 and 5 possessed potent cell growth inhibitory effects. GCMs of fractions 4 and 5 showed they possessed numerous saturated fatty acids with pharmacological relevance. The presence of these compounds shows potential for exploitation of D. alata extracts for pharmacological purposes. Full article

Field and storage trials were conducted to assess the response of exotic and local yam genotypes to major diseases (anthracnose, yam mosaic virus (YMV) and dry rot) and pests (i.e., mealy bug and nematodes) for the identification of parents with desired complementary traits for crossing. The experiment was conducted at the Njala Agricultural Research Centre (NARC) experimental site in Sierra Leone during two cropping seasons, 2020 and 2021. A total of 113 genotypes of yam comprising 15 D. rotundata, 4 D. prahensilis, 7 D. esculenta, 74 D. alata, 7 D. bulbifera, and 4 D. cayenensis were assessed. Results showed a significant (p < 0.001) linear relationship between yield and disease severity among yam genotypes. In-field disease (anthracnose and yam mosaic virus) infection accounted for 38% of the total variation observed in the fresh tuber yield. Findings on fresh tuber yield revealed that for every ton increase in yield of yams, anthracnose and YMV severities at five months after planting (MAP) decreased by 0.5 and 3.1 units, respectively. About 30 genotypes had low infection of disease, of which two belonged to D. rotundata (TDr 205 and TDr 96/00587), two belonged to D. prahensilis (PSLY074-13 and BMSLY085-13), three belonged to D. bulbifera (MOSLY022-12, MOSLY024-12 and KESLY09-12), and one belonged to D. esculenta (WRSLY083-13), while the remaining were D. alata. About 27 genotypes had intermediate infection, and 14 had high disease susceptibility, all of which belonged to D. alata. Storage disease infection had a highly significant (p < 0.002) linear relationship among yam genotypes. Dry rot, mealy bug, and nematode infection accounted for 15.1% of the total variation in fresh tuber weight loss. The findings were relevant for selecting parents with complementary traits of interest targeted at yam population improvement. Full article

Yam (Dioscorea spp.) productivity is constrained significantly by the lack of a formal seed system. Vegetative propagation, through tuber setts as ‘seed’ yams, encourages the recycling of virus-infected planting materials, contributing to high virus incidence and yield losses. Efforts are ongoing to increase the production of high-quality seed yams in a formal seed system to reduce virus-induced yield losses and enhance the crop’s productivity and food security. Specific and sensitive diagnostic tests are imperative to prevent the multiplication of virus-infected materials contributing to a sustainable seed yam certification system. During routine indexing of yam accessions, discrepancies were observed between the results obtained from the reverse transcription loop-mediated isothermal amplification (RT-LAMP) test and those from reverse transcription polymerase chain reaction (RT-PCR); RT-LAMP failed to detect Yam mosaic virus (YMV) in some samples that tested positive by RT-PCR. This prompted the design of a new set of LAMP primers, YMV1-OPT primers. These primers detected as little as 0.1 fg/µL of purified RNA obtained from a YMV-infected plant, a sensitivity equivalent to that obtained with RT-PCR. RT-LAMP using YMV1-OPT primers is recommended for all future virus-indexing of seed yams for YMV, offering a rapid, sensitive, and cost-effective approach. Full article

Dioscorea spp. belongs to the Dioscoreaceae family, known as “yams”, and contains approximately 600 species with a wide distribution. It is a major food source for millions of people in tropical and subtropical regions. Dioscorea has great medicinal and therapeutic capabilities and is a potential source of bioactive substances for the prevention and treatment of many diseases. In recent years, increasing attention has been paid to the phytochemicals of Dioscorea, such as steroidal saponins, polyphenols, allantoin, and, in particular, polysaccharides and diosgenin. These bioactive compounds possess anti-inflammatory activity and are protective against a variety of inflammatory diseases, such as enteritis, arthritis, dermatitis, acute pancreatitis, and neuroinflammation. In addition, they play an important role in the prevention and treatment of metabolic diseases, including obesity, dyslipidemia, diabetes, and non-alcoholic fatty liver disease. Their mechanisms of action are related to the modulation of a number of key signaling pathways and molecular targets. This review mainly summarizes recent studies on the bioactive compounds of Dioscorea and its treatment of inflammatory and metabolic diseases, and highlights the underlying molecular mechanisms. In conclusion, Dioscorea is a promising source of bioactive components and has the potential to develop novel natural bioactive compounds for the prevention and treatment of inflammatory and metabolic diseases. Full article

Yam (Dioscorea spp.) is an important food security crop with economic, nutritional, and medicinal value. It is a source of carbohydrates for millions of people in tropical and sub-tropical regions of Africa, Asia, South America, the Caribbean, and the South Pacific Islands. Determining the appropriate parents for breeding programs is the most important decision that plant breeders must make to maximize genetic variability and produce excellent recombinant varieties. However, adequate genetic diversity and the population structure of yam accessions in Kenya are not available to guide accurate selection of parents for breeding. In the present study, 25 start-codon-targeted (SCoT) molecular markers were used to determine the genetic diversity and population structure among 20 yam accessions grown in Kenya. A total of 294 fragments were amplified, of which 95% were polymorphic with an average of 11.16 polymorphic fragments per primer. The polymorphic information content (PIC) value and primer resolving power (Rp) of 0.58 and 5.91, respectively, revealed high genetic diversity among the accessions. A dendrogram based on the unweighted pair group method of arithmetic means (UPGMA) grouped the 20 yam accessions into two clusters at 0.61 genetic similarity coefficients. Bayesian structure analysis revealed the existence of three subpopulations and some admixed accessions. Analysis of molecular variance (AMOVA) revealed a variance of 60% within the subpopulations and 40% among the subpopulations. The high degree of genetic diversity in the yam accessions successfully exhibited by SCoT molecular markers may serve as a valuable aid to widen the genetic base in yam breeding programs. The selection and hybridization of parental lines from the different clusters and sub-clusters identified could provide a foundation and could be exploited for yam breeding and variety development. Full article

Yams (Dioscorea spp.) are a pantropical genus located worldwide that constitute an important source of nutrients and pharmaceutical substances. Some Dioscorea crop species are widely grown in West Africa. One species that is mainly cultivated in Cameroon is Dioscorea dumetorum. This is a dioecious root crop whose sex-determining system was unknown until now. To address the possible presence of sex chromosomes in D. dumetorum, we performed a karyotype characterization of male and female individuals using classical and molecular cytogenetic approaches. It was determined that 2n = 40 was the most common number of chromosomes in all of the investigated samples. One chromosome pair was longer than the others in the chromosome set and was a heteromorph in male and homomorph in female individuals. This pair corresponded to sex chromosomes, and we also confirmed this with molecular cytogenetic experiments. The results of chromomycin banding revealed the presence of strong positive signals on this chromosome pair. The signals, corresponding to GC-rich DNA regions, were similar in size on the chromosomes of the female individuals, whereas they were different in size in the male individuals. This size difference in the GC-rich heterochromatin regions was also apparent in the interphase nuclei as one small and one large fluorescent spot. The results of the in situ hybridization experiment showed that these chromomycin positive signals on the sex chromosomes also corresponded to the 35S rDNA cluster. The mean 2C DNA value (genome size) obtained for D. dumentorum was 0.71 pg (±0.012), which represents a small genome size. We found no difference in the genome size between the male and female individuals. The results of this study contribute to increasing our knowledge of sex determination in D. dumetorum (standard sex-determining XX/XY system) and may have some agronomic applications. Full article