Jasmonic acid enhances thermotolerance in hybrid Pennisetum via activation of the α-linolenic acid metabolism pathway

In this study, we investigated the role of jasmonic acid (JA) in the heat tolerance of Pennisetum americanum×P.purpureum cv.Minmu 6 ; high temperatures generally cause leaf yellowing, dehydration, and reductions in chlorophyll and water contents, indicating photosynthetic disruption, and RNA-seq revealed significant α-linolenic acid metabolism pathway enrichment, with key JA biosynthesis genes ( PLA2H3 , LOX8 , AOS1 , AOS2 , OPR 1, and OPR11 ) markedly upregulated and endogenous JA levels elevated. Exogenous JA application alleviated this heat damage, maintained higher chlorophyll and water contents, and enhanced JA-related gene expression; qPCR confirmed JA’s positive feedback regulation within this pathway, with LOX8 and OPR11 showing strong responsiveness. Overall, heat stress activates α-linolenic acid metabolism to promote JA accumulation, while exogenous JA amplifies this response, improving heat tolerance; these findings elucidate a JA-mediated regulatory mechanism of thermotolerance and provide a theoretical basis for enhancing heat resilience in forage crops.