Comparative Transcriptome, Metabolome, and Ionome Analysis of Two Contrasting Common Bean Genotypes in Saline Conditions

Abstract

Soil salinity is a major abiotic stress factor that limits agricultural productivity worldwide, and this problem is expected to grow in the future. Common bean is an important protein source in developing countries however highly susceptible to salt stress. To understand the underlying mechanism of salt stress responses, transcriptomics, metabolomics, and ion content analysis were performed on both salt-tolerant and susceptible common bean genotypes in saline conditions. Transcriptomics has demonstrated increased photosynthesis in saline conditions for tolerant genotype while the susceptible genotype acted in contrast. Transcriptome also displayed active carbon and amino-acid metabolism for the tolerant genotype. Analysis of metabolites with GC-MS demonstrated the boosted carbohydrate metabolism in the tolerant genotype with increased sugar content as well as better amino-acid metabolism. Accumulation of lysine, valine, and isoleucine in the roots of the susceptible genotype suggested a halted stress response. 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 dropped in the tolerant roots, while Mo+2 levels were significantly higher in all tissues in both control and saline conditions for tolerant genotype. 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.

pvSPS4 is Crucial for the Root Sugar Balance and Proper Tolerance Response in Salt-Tolerant Common Bean Genotype Under Salt Stress

“…7). pvSPS4 knock-down had a major effect on both uptake and transport of the K + : Blank and HumFer root K + levels acted in concert with previous results for Ispir genotype (Niron et. al.…”

“…2020) and dropped signi cantly under salt stress while SucPho root K + levels signi cantly increased (Fig. 6a) as observed in a salt susceptible genotype (Niron et. al.…”

“…The change in this ratio for SucPho roots was overall 2.71 times higher than the roots of other lines upon salt treatment. Interestingly, in our previous study, a similar difference was observed between the roots of the salt-tolerant Ispir and salt-susceptible TR43477 genotypes, with the latter displaying a 2.35 times greater decrease under salt-stress (Niron et al 2020). The similarity of this variation suggests that it can be a key subject for the salt tolerance response.…”

“…The other SPS homolog, pvSPS3, had very low transcript levels in wild-type root tissues, but a high level of expression in leaves. pvSPS3 also displayed a upregulation in the leaves upon salt stress which indicates a leaf-speci c regulation for this gene (Niron et al 2020).…”

“…This revealed a major distinction in carbohydrate metabolism between these genotypes: The tolerant genotype Ispir accumulated greater levels of soluble carbohydrates in the roots compared to the susceptible genotype (TR43477). Together with this accumulation, a sucrose phosphate synthase (SPS) gene displayed a sharp upregulation in expression in the tolerant genotype that is absent in the susceptible genotype (Niron et al 2020). SPS enzymes act in the rst step of the sucrose synthesis pathway with the transfer of a glycosyl group from an activated sugar donor such as uridine diphosphate glucose to an acceptor fructose-6'-phosphate to generate sucrose-6'-phosphate (Chua et al 2008).…”