Transcriptional reprogramming of heat-sensitive maize anther development under heat stress

Heat stress during anther development severely impairs pollen fertility and substantially reduces yield. However, how heat stress reshapes transcriptional programs at specific anther developmental stages and which regulatory mechanisms underlie stage-dependent sensitivity remain unclear. Here, we used the heat-sensitive inbred line Zheng641 as a model to characterize fine-scale transcriptional responses to heat stress. Morphological analyses showed that elevated temperatures markedly reduced tassel branch number and pollen viability and delayed tapetal degradation. High-resolution transcriptomic profiling revealed that heat stress mainly activated the pathways related to fatty acid biosynthesis and carbohydrate metabolism during the early stage of pollen development, whereas late-stage heat stress induced amino acid transport and biosynthesis while repressing cell wall modification and protein folding. Phase‐specific transcription factor analysis indicated that bHLHs transcription factor were significantly enriched before the tetrad stage, AP2/ERFs in microspore stage, MYBs in pollen mature stage. Furthermore, we explored Zm00001eb296990 could improve thermotolerance by the phenotypic analysis of transgenic overexpressed lines. Notably, the function-loss of Zm00001eb296990 significantly reduced pollen viability and seed set under heat stress. Together, these findings provide a high-resolution transcriptomic framework for understanding the molecular basis of maize anther sensitivity to heat and identify promising targets for enhancing thermotolerance in maize breeding.