Transcriptomic analysis of salt tolerance-associated genes and diversity analysis using indel markers in yardlong bean (Vigna unguiculata ssp. sesquipedialis)

Nutritional Qualities, Metabolite Contents, and Antioxidant Capacities of Yardlong Beans (Vigna unguiculata subsp. sesquipedalis) of Different Pod and Seed Colors

Studying the effects of genetic and environmental factors on plant biochemical components helps in selecting the best varieties for the food industry and breeding programs. This study analyzed the nutritional qualities, secondary metabolites, and antioxidant activities of 14 field-grown yardlong beans accessions and how they are affected by differences in pod and seed colors. The analyzed parameters varied significantly among the yardlong bean accessions, with variances ranging from 1.36% in total unsaturated fatty acid content to 51.01% in DPPH• scavenging activity. Accessions YLB4, YLB7, and YLB14 performed the best, showing antioxidant indices of 100.00, 70.10, and 67.88%, respectively. Among these, YLB14 showed a characteristic property, having the highest levels of vitamin C (2.62 mg/g) and omega-6 to omega-3 ratio (2.67). It also had the second highest dietary fiber (21.45%), stearic acid (4.44%), and linoleic acid (40.39%) contents, as well as the lowest thrombogenicity index (0.38). Although cluster and principal component analyses did not clearly separate the yardlong beans based on pod or seed color, analysis of variance revealed that these factors and their interaction had significant effects on total phenol, DPPH• scavenging activity, ABTS•+ scavenging activity, and reducing power. In contrast, the nutritional parameters, except for dietary fiber, were not significantly affected by pod and seed color variations. Therefore, consuming yardlong beans of different pod and seed colors may not affect the overall nutrient intake. In general, this study identified yardlong beans with green pods and black seeds as good sources of antioxidants. Accordingly, further metabolomics and genomics studies are suggested to thoroughly explore their characteristics.

Enhancing cowpea wilt resistance: insights from gene coexpression network analysis with exogenous melatonin treatment

BACKGROUND

Cowpea wilt is a harmful disease caused by Fusarium oxysporum, leading to substantial losses in cowpea production. Melatonin reportedly regulates plant immunity to pathogens; however the specific regulatory mechanism underlying the protective effect of melatonin pretreated of cowpea against Fusarium oxysporum remains known. Accordingly, the study sought to evaluate changes in the physiological and biochemical indices of cowpea following melatonin treated to facilitate Fusarium oxysporum resistance and elucidate the associated molecular mechanism using a weighted gene coexpression network.

RESULTS

Treatment with 100 µM melatonin was effective in increasing cowpea resistance to Fusarium oxysporum. Glutathione peroxidase (GSH-PX), catalase (CAT), and salicylic acid (SA) levels were significantly upregulated, and hydrogen peroxide (H2O2) levels were significantly downregulated in melatonin treated samples in roots. Weighted gene coexpression network analysis of melatonin- and Fusarium oxysporum-treated samples identified six expression modules comprising 2266 genes; the number of genes per module ranged from 9 to 895. In particular, 17 redox genes and 32 transcription factors within the blue module formed a complex interconnected expression network. KEGG analysis revealed that the associated pathways were enriched in secondary metabolism, peroxisomes, phenylalanine metabolism, flavonoids, and flavonol biosynthesis. More specifically, genes involved in lignin synthesis, catalase, superoxide dismutase, and peroxidase were upregulated. Additionally, exogenous melatonin induced activation of transcription factors, such as WRKY and MYB.

CONCLUSIONS

The study elucidated changes in the expression of genes associated with the response of cowpea to Fusarium oxysporum under melatonin treated. Specifically, multiple defence mechanisms were initiated to improve cowpea resistance to Fusarium oxysporum.

RNA-Seq-Based WGCNA and Association Analysis Reveal the Key Regulatory Module and Genes Responding to Salt Stress in Wheat Roots

Soil salinization is the main abiotic stressor faced by crops. An improved understanding of the transcriptional response to salt stress in roots, the organ directly exposed to a high salinity environment, can inform breeding strategies to enhance tolerance and increase crop yield. Here, RNA-sequencing was performed on the roots of salt-tolerant wheat breeding line CH7034 at 0, 1, 6, 24, and 48 h after NaCl treatment. Based on transcriptome data, a weighted gene co-expression network analysis (WGCNA) was constructed, and five gene co-expression modules were obtained, of which the blue module was correlated with the time course of salt stress at 1 and 48 h. Two GO terms containing 249 differentially expressed genes (DEGs) related to osmotic stress response and salt-stress response were enriched in the blue module. These DEGs were subsequently used for association analysis with a set of wheat germplasm resources, and the results showed that four genes, namely a Walls Are Thin 1-related gene (TaWAT), an aquaporin gene (TaAQP), a glutathione S-transfer gene (TaGST), and a zinc finger gene (TaZFP), were associated with the root salt-tolerance phenotype. Using the four candidate genes as hub genes, a co-expression network was constructed with another 20 DEGs with edge weights greater than 0.6. The network showed that TaWAT and TaAQP were mainly co-expressed with fifteen interacting DEGs 1 h after salt treatment, while TaGST and TaZFP were mainly co-expressed with five interacting DEGs 48 h after salt treatment. This study provides key modules and candidate genes for understanding the salt-stress response mechanism in wheat roots.

Exploiting genetic and genomic resources to enhance productivity and abiotic stress adaptation of underutilized pulses

Underutilized pulses and their wild relatives are typically stress tolerant and their seeds are packed with protein, fibers, minerals, vitamins, and phytochemicals. The consumption of such nutritionally dense legumes together with cereal-based food may promote global food and nutritional security. However, such species are deficient in a few or several desirable domestication traits thereby reducing their agronomic value, requiring further genetic enhancement for developing productive, nutritionally dense, and climate resilient cultivars. This review article considers 13 underutilized pulses and focuses on their germplasm holdings, diversity, crop-wild-crop gene flow, genome sequencing, syntenic relationships, the potential for breeding and transgenic manipulation, and the genetics of agronomic and stress tolerance traits. Recent progress has shown the potential for crop improvement and food security, for example, the genetic basis of stem determinacy and fragrance in moth bean and rice bean, multiple abiotic stress tolerant traits in horse gram and tepary bean, bruchid resistance in lima bean, low neurotoxin in grass pea, and photoperiod induced flowering and anthocyanin accumulation in adzuki bean have been investigated. Advances in introgression breeding to develop elite genetic stocks of grass pea with low β-ODAP (neurotoxin compound), resistance to Mungbean yellow mosaic India virus in black gram using rice bean, and abiotic stress adaptation in common bean, using genes from tepary bean have been carried out. This highlights their potential in wider breeding programs to introduce such traits in locally adapted cultivars. The potential of de-domestication or feralization in the evolution of new variants in these crops are also highlighted.

Molecular Pathways of WRKY Genes in Regulating Plant Salinity Tolerance

Salinity is a natural and anthropogenic process that plants overcome using various responses. Salinity imposes a two-phase effect, simplified into the initial osmotic challenges and subsequent salinity-specific ion toxicities from continual exposure to sodium and chloride ions. Plant responses to salinity encompass a complex gene network involving osmotic balance, ion transport, antioxidant response, and hormone signaling pathways typically mediated by transcription factors. One particular transcription factor mega family, WRKY, is a principal regulator of salinity responses. Here, we categorize a collection of known salinity-responding WRKYs and summarize their molecular pathways. WRKYs collectively play a part in regulating osmotic balance, ion transport response, antioxidant response, and hormone signaling pathways in plants. Particular attention is given to the hormone signaling pathway to illuminate the relationship between WRKYs and abscisic acid signaling. Observed trends among WRKYs are highlighted, including group II WRKYs as major regulators of the salinity response. We recommend renaming existing WRKYs and adopting a naming system to a standardized format based on protein structure.