Project description:Common bean (Phaseolus vulgaris L.) is a relevant crop cultivated over the world, largely in water insufficiency vulnerable areas. Since drought is the main environmental factor restraining worldwide crop production, efforts have been invested to amend drought tolerance in commercial common bean varieties. However, scarce molecular data are available for those cultivars of P. vulgaris with drought tolerance attributes. As a first approach, Pinto Saltillo (PS), Azufrado Higuera (AH), and Negro Jamapa Plus (NP) were assessed phenotypically and physiologically to determine the outcome in response to drought on these common bean cultivars. Based on this, a Next-generation sequencing approach was applied to PS, which was the most drought-tolerant cultivar to determine the molecular changes at the transcriptional level. The RNA-Seq analysis revealed that numerous PS genes are dynamically modulated by drought. In brief, 1005 differentially expressed genes (DEGs) were identified, from which 645 genes were up-regulated by drought stress, whereas 360 genes were down-regulated. Further analysis showed that the enriched categories of the up-regulated genes in response to drought fit to processes related to carbohydrate metabolism (polysaccharide metabolic processes), particularly genes encoding proteins located within the cell periphery (cell wall dynamics). In the case of down-regulated genes, heat shock-responsive genes, mainly associated with protein folding, chloroplast, and oxidation-reduction processes were identified. Our findings suggest that secondary cell wall (SCW) properties contribute to P. vulgaris L. drought tolerance through alleviation or mitigation of drought-induced osmotic disturbances, making cultivars more adaptable to such stress. Altogether, the knowledge derived from this study is significant for a forthcoming understanding of the molecular mechanisms involved in drought tolerance on common bean, especially for drought-tolerant cultivars such as PS.
Project description:Background: Soil salinity is a major abiotic stress factor that limit agricultural productivity worldwide, and this problem is expected to grow in the future. Common bean (Phaseolus vulgaris L.) is an important protein source in developing countries is highly susceptible to salt stress. To understand the underlying mechanism of salt stress responses, transcriptomics, metabolomics, and ion content analysis were utilized for response comparison of salt-tolerant and salt-susceptible common bean genotypes in saline conditions. Results: Transcriptome analysis has revealed that the tolerant genotype had increased photosynthesis in saline conditions while the susceptible genotype acted in a contrasting way. The chlorophyll content measurements have backed up this result with increase in tolerant and decrease in susceptible genotype. Transcriptome also displayed a more active carbon and amino acid metabolism for the tolerant genotype as well. Analysis of primary metabolites with GC-MS demonstrated the boosted carbohydrate metabolism in the tolerant genotype with increased sugar content as well as better amino-acid metabolism with the accumulation of glutamate and asparagine and hinted a lowered photorespiration level for the tolerant one. Accumulation of lysine, valine, and isoleucine in the roots of the susceptible genotype suggested a halted stress response pathway. According to ion content comparison, the tolerant genotype managed to block accumulation of Na+ in the leaves while accumulating significantly less Na+ in the roots compared to susceptible genotype. K+ levels increased in the leaves of both genotype and the roots of the susceptible one but dropped in the roots of the tolerant genotype. Additionally, Zn+2 and Mn+2 levels were also dropped in the tolerant roots, while Mo+2 levels were significantly higher in all tissues in both control and saline conditions for tolerant genotype. Conclusion:The results of the presented study have demonstrated the differences in contrasting genotypes and thus provide valuable information on the pivotal molecular mechanisms underlying salt tolerance mainly in common bean, but for all crops.
Project description:Drought is a major limiting constraint to faba bean production worldwide, including Tunisia. However, molecular mechanisms underlying faba bean responses to drought stress are not well understood. In this context, transcriptome analysis by RNA-seq was performed to investigate drought-related genes and construct a network of faba bean drought stress response and tolerance. De novo assembly of the transcriptome generated 26,728 differentially expressed genes (DEGs). Of these, 13,920 were up-regulated and 12,808 down-regulated in faba bean drought-stressed leaves. Moreover, a total of 10,800 simple sequence repeats (SSRs) and 2130 transcription factors involved in major metabolic pathways including abscisic acid (ABA)-dependent and -independent signaling pathway were identified. GO, KOG and KEGG enrichment analyses revealed that these DEGs were involved in several important processes including photosynthesis, flavonoid biosynthesis, response to stimulus and abiotic stress, reactive oxygen species (ROS) scavengers, signal transduction, biosynthesis of secondary metabolites and transporters, suggesting the involvement of these important pathways in faba bean response to water deficit. Various stress proteins such as late embryogenesis abundant proteins (LEA), dehydrins (DHNs) and heat shock proteins (HSPs) have been identified and their expression was robustly upregulated in drought-stressed leaves, indicating their key contribution to drought response and adaptation by conferring protection and providing stability to faba bean plant cellular processes under water deficit. The reliability of the RNA-seq results was confirmed by the analysis of 10 randomly selected genes using qRT-PCR. Taken together, these findings help advancing our knowledge and can guide breeding programs aimed at improving the tolerance of faba bean to drought stress.
Project description:A wide range of environmental stresses lead to an elevated production of reactive oxygen species (ROS) in plant cells thus resulting in oxidative stress. The biological nitrogen fixation in the legume - Rhizobium symbiosis is at high risk of damage from oxidative stress. Common bean (Phaseolus vulgaris) active nodules exposed to the herbicide Paraquat (1,1 '-Dimethyl-4, 4'-bipyridinium dichloride hydrate) that generates ROS accumulation, showed a reduced nitrogenase activity and ureide content. We analyzed the global gene response of stressed nodules using the Bean CombiMatrix Custom Array 90K, that includes probes from some 30,000 expressed sequence tags (EST). A total of 4,280 ESTs were differentially expressed in oxidative stressed bean nodules; of these 2,218 were repressed. These genes were grouped in 44 different biological processes as defined by Gene Onthology. Analysis with the PathExpress bioinformatic tool, adapted for bean, identified five significantly repressed metabolic path