JA-mediated defence activation underlies Chilo partellus tolerance in maize: Evidence from integrative multi-omics analyses

Maize faces substantial yield losses from herbivory by the spotted stemborer Chilo partellus , and understanding defence mechanisms is critical for breeding resilient cultivars. In this study, two maize inbred lines, BML 6 (susceptible) and BML 7 (tolerant), and their hybrid DHM 117, were evaluated for resistance, revealing that BML 7 reduced larval establishment and growth, BML 6 supported higher larval survival, and the hybrid exhibited intermediate resistance with increased biomass, reflecting partial inheritance of defence traits. Transcriptomic and RT-PCR analyses demonstrated that jasmonic acid (JA) mediated signalling orchestrates maize defence, with strong induction of key genes in BML 7 and DHM 117, including Lipoxygenase 2/3/5 (LOXs), Fatty acid α-dioxygenase (FAD1), Terpene synthases 4/10 (TPS4/10), α-terpineol synthase, Cystatin 2, Anthranilate synthase α-subunit 1 (ASα1), and Anthranilic acid methyltransferase 1 (AAMT1), driving terpenoid and benzoxazinoid biosynthesis, whereas BML 6 primarily activated the phenylpropanoid pathway. Metabolomic profiling (UPLC-QTOF-MS) revealed that BML 7 accumulated specialized metabolites, including phenolic acid–flavonoid conjugates, while BML 6 showed higher levels of simple phenolics, linking metabolite composition to larval performance. Overall, the integration of phenotypic, transcriptomic, and metabolomic evidence underscores the central role of JA signalling and its downstream defence network in maize, identifying functional molecular markers for developing pest-resilient cultivars.