DNA TOP1α coordinates anther morphogenesis and fertility through gene regulatory networks in arabidopsis.

DNA topoisomerase 1 alpha (TOP1α) plays a critical role in plant development, yet its specific involvement in male reproduction is not well understood. Here, we show that TOP1α is essential for Arabidopsis anther development, and its absence leads to severe morphological and functional defects. The top1α1 mutant displays pleiotropic phenotypes, including early flowering and twisted petals, most notably the loss of two microsporangia. This loss stems from disrupted cell division in the L2 layer. Cytological analyses reveal aberrant pollen wall formation and reduced fertility in the mutant. RNA-seq data from top1α1 mutants identify over 2,000 differentially expressed genes, with significant downregulation of key anther development regulators such as SPL, AMS, and MS1, alongside genes involved in proteostasis and lipid metabolism. Furthermore, chromatin immunoprecipitation (ChIP) confirms TOP1α directly binds to the promoters of crucial genes like AG, MS1, and MYB80, suggesting a role in modulating transcriptional accessibility. All observed defects were rescued by complementation with gTOP1α-4HA, confirming the specificity of the top1α1 phenotype. Our findings establish TOP1α as a central coordinator of anther morphogenesis, functioning through intricate gene regulatory networks and chromatin remodeling. This work provides novel insights into the molecular mechanisms governing male reproductive development in plants.