Transcriptome analysis reveals the role of jasmonate in regulating maize spikelet opening and seed set under high temperature stress.

Introduction: Maize is a crucial cereal crop, yet it is highly susceptible to heat stress, which considerably limits its grain yield. The opening of spikelets is a critical prerequisite for pollen shedding. Jasmonate (JA) plays significant roles in responding to abiotic stress and regulating spikelet development in plants. Methods: To investigate the molecular mechanisms underlying heat tolerance in maize, a heat-tolerant inbred line, Chang 7-2 (C7), and two heat-sensitive inbred lines, Yu727 and Y8201 (Y7 and Y8), were exposed to heat stress, followed by JA application, and subsequently analyzed using RNA sequencing. Results and Discussion: Our results indicate that under heat stress conditions, JA markedly enhances the seed-setting rate, spikelet opening rate, and spikelet opening angle in both Y7 and Y8. Moreover, JA effectively alleviates oxidative stress induced by heat stress in maize. KEGG analysis identified phenylpropanoid biosynthesis, flavonoid biosynthesis, and starch and sucrose metabolism as potential contributors to JA-mediated heat stress resistance in maize. Finally, Venn analysis of differentially expressed genes (DEGs) identified three transcription factors (TFs) involved in JA-mediated heat stress resistance in maize: MYBS3 and WRKY33, which play positive roles, and HOX22, which plays a negative role. Our findings collectively elucidate a fundamental regulatory network mediated by JA that enhances maize yield under heat stress conditions, offering viable gene targets for the genetic enhancement of maize yield in such environments.