Green leaf volatile (Z)-3-hexeny-1-yl acetate reduces salt stress in peanut by regulating photosynthesis and cellular redox homeostasis

Green leaf volatiles (GLVs) are released by plants when they encounter biotic stress, but their functions in the response of plants to abiotic stress have not been determined. Previously, we showed that exogenous application of (Z)-3-hexeny-1-yl acetate (Z-3-HAC), a kind of GLV, could alleviate salt stress in peanut (Arachis hypogaea L.) seedlings; however, notably little is known concerning the transcription regulation mechanisms of Z-3-HAC. In this study, we comprehensively characterized the transcriptomes and physiological indices of peanut seedlings exposed to Z-3-HAC and/or salt stress. The results revealed that Z-3-HAC significantly increased the net photosynthetic rate, SPAD value, plant height, and shoot biomass compared with the non-primed peanut seedlings under salt stress. A significantly higher ratio of K+ : Na+, reduced to oxidized glutathione (GSH : GSSG), and ascorbate to dehydroascorbate (AsA : DHA) were observed for the plants primed with Z-3-HAC compared with the salt stress control; meanwhile, Z-3-HAC increased the activity of enzymes in the AsA-GSH cycle and cellular redox homeostasis. Analysis of transcriptome data showed that 1,420 genes were upregulated in the Z-3-HAC + NaCl treatment compared with the NaCl treatment. Interestingly, these genes were significantly enriched in the photosynthetic and ascorbate metabolism-related categories. Taken together, these results highlight the importance of Z-3-HAC in protecting peanut seedlings against salt stress through the regulation of photosynthesis, cellular redox homeostasis, and K+ : Na+ homeostasis.