Integrative metabolomic and transcriptional regulation insights reveal salt-tolerance in rice landrace 'Korgut' (Oryza sativa L.)

Abstract

Salt stress is a major environmental challenge that affects plant growth and productivity. Rice showcases remarkable genetic diversity, with certain salt-tolerant genotypes and traditional varieties exhibiting diverse metabolites essential for stress alleviation, and some of these genotypes remain unexplored. In this study, we investigated the morphological, biochemical, molecular, and metabolic responses of the indigenous salt-tolerant rice landrace of Goa "Korgut" and the salt-sensitive variety IR64 to salt stress. As per this study Korgut exhibited better growth parameters compared to IR64 under salt stress, indicating superior stress tolerance. We analyzed the expression of salt-tolerant genes MYC, DREB2A, PIP2A, and SOS1 in both varieties. The results showed upregulation of these genes in response to salt stress, with Korgut demonstrating higher expression levels than IR64. Phenolic accumulation was examined in both leaf and culm tissues, revealing increased phenolic content in Korgut compared to IR64 after NaCl treatment. Quantitative assays confirmed higher total phenolics and flavonoids in Korgut, supporting its enhanced stress tolerance. The gene expression of flavonoid biosynthetic enzymes LAR, NOMT, F3H was found to be higher in Korgut than IR64 under salt stress. Moreover, GC-MS analysis identified the metabolites involved in the salt stress response. The heat map revealed distinct metabolic profiles for Korgut and IR64, with Korgut showing a more robust metabolic response to NaCl treatment. This study highlights the adaptive mechanisms of Korgut under salt stress, including enhanced stress-responsive gene expression, higher secondary metabolite accumulation. Our findings unveil possible candidate metabolites associated with salt tolerance in indigenous rice, offering valuable insights for further research in developing salt-tolerant cultivars through conventional breeding, genetic engineering, or exogenous application of metabolites.