The glutathione-related metabolism and the AhGST23 gene mediate drought and salt stresses tolerance in peanut (Arachis hypogaea L.)
Abstract
Abiotic stresses such as drought and salinity significantly constrain peanut productivity. However, their underlying molecular response mechanisms remain unclear. This study identified the AhGST23 gene, together with its involvement in glutathione metabolism and the ascorbic acid-glutathione (AsA-GSH) cycle, as a key component in alleviating drought and salt stresses in peanut. Under drought (15% PEG6000 for 6 days) and salt (200 mM NaCl for 6 days) stresses, peanut seedlings exhibited a marked reduction in biomass, net photosynthetic rate, transpiration rate, and chlorophyll fluorescence parameters. Concurrently, levels of H2O2, O2−, and malondialdehyde (MDA), as well as the activities of antioxidant enzymes (APX, GR, SOD, POD, and CAT), were significantly elevated in both leaves and roots. RNA-seq analysis identified 3,780 and 5,019 shared differentially expressed genes (DEGs) in leaves and roots, respectively, which were enriched in pathways including plant hormone signal transduction, starch and sucrose metabolism, glutathione metabolism, and MAPK signaling. The key gene families involved in the glutathione metabolism (AhGSTs, AhGPXs) and AsA-GSH cycle (AhGRs, AhAPXs, and AhMDHARs) were highlighted as central players in the antioxidant system. Silencing AhGST23 disrupted glutathione-related metabolism in peanut. This disruption was manifested by reduced contents of ascorbic acid (AsA), dehydroascorbate (DHA), glutathione (GSH), and oxidized glutathione (GSSG), as well as decreased activities of ascorbate eroxidase (APX), glutathione S-transferases (GST), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR). These disruptions impaired ROS scavenging capacity and heightened sensitivity to drought and salt stresses. In summary, the glutathione-related metabolism, with AhGST23 as a key functional gene, plays an essential role in conferring drought and salt stresses tolerance in peanut. These findings offer novel insights into antioxidant defense mechanisms and provide valuable genetic resources for enhancing peanut stress resilience.