Transcriptomic analysis of enhanced heat tolerance in maize via spray-induced gene silencing targeting ZmHSF20

This study utilized Spray-Induced Gene Silencing (SIGS) technology to systematically characterize the molecular mechanisms underlying enhanced heat tolerance in maize. By exogenously applying synthetic small RNA (atsRNA-HSF20) to target and silence the maize heat shock transcription factor gene ZmHSF20, leaf samples were collected from maize plants at the V3 (three-leaf) stage under both ambient temperatures (24/20 degrees C, day/night) and heat stress (45 degrees C for 24 hours) for transcriptome sequencing (RNA-seq) analysis. The results demonstrated that the silencing of ZmHSF20 relieved its inhibitory effects on the downstream positive regulator ZmHSF4 and the cellulose synthase gene ZmCESA2, thereby activating the "ZmHSF20-ZmHSF4-ZmCESA2" regulatory module. Differentially expressed gene (DEG) analysis identified 3,271 DEGs under ambient conditions and 7,109 DEGs under heat stress. Notably, up-regulated genes were significantly enriched in pathways related to cell wall organization, cellulose biosynthesis, photosynthesis, and carbon fixation. This research represents the first non-transgenic validation of the negative regulatory role of ZmHSF20 in maize heat tolerance. It highlights the critical importance of cell wall remodeling in enhancing crop resilience to thermal stress, providing a vital theoretical foundation and data resource for developing environment-friendly strategies for crop stress protection.