The ascorbate-glutathione cycle (AsA-GSH) and the AhGST23 gene mediate drought and salt stress tolerance in peanut (Arachis hypogaea L.)

Background Abiotic stresses such as drought and salinity significantly constrain peanut productivity, nevertheless, their underlying molecular response mechanisms remain unclear. Results This study identifies the ascorbate-glutathione cycle (AsA-GSH) and AhGST23 gene as crucial components in mitigating drought and salt stress in peanut. Under drought (15% PEG6000 for 6 days) and salt (200 mM NaCl for 6 days) stress, peanut seedlings exhibited a marked reduction in biomass, net photosynthetic rate, transpiration rate, and chlorophyll fluorescence parameters. Concurrently, levels of H ₂ O ₂ , O ₂ ⁻ , 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 AsA-GSH cycle ( AhGRs , AhGSTs , AhGPXs , and AhAPXs ) were highlighted as central players in the antioxidant system. Silencing AhGST23 disrupted the AsA-GSH cycle in peanut. This disruption was manifested by reduced contents of AsA, DHA, GSH, and GSSG, as well as decreased activities of APX, GST, DHAR, and MDHAR. These disruptions impaired ROS scavenging capacity and heightened sensitivity to drought and salt stress. Conclusions In summary, the AsA-GSH cycle, with AhGST23 as a key regulatory element, plays an essential role in conferring drought and salt stress tolerance in peanut. These findings offer novel insights into antioxidant defense mechanisms and provide valuable genetic resources for enhancing peanut stress resilience.