Systematic Analysis of Fertility Conversion via WGCNA Implicates a Compensatory Regulatory Network in a Reverse Thermosensitive Genic Male Sterility Line of Eggplant (Solanum melongena L.).

Thermosensitive genic male sterility (TGMS) lines are vital for two-line hybrid breeding. However, the molecular mechanism in the reverse TGMS line 05ms in eggplant remains unclear. Weighted gene co-expression network analysis (WGCNA) of RNA-seq data revealed modules correlated with fertility conversion enriched in carbohydrate metabolism, lipid metabolism, and mRNA surveillance pathways. Hub genes within these modules were predominantly associated with sugar-related processes, fatty acid metabolism, and nucleotide processing. BSA-seq defined candidate genomic intervals. Integrated analysis of BSA-seq intervals and transcriptomic data identified a candidate gene, SmHTH, with consistently lower expression in 05ms compared to S63. Its homologs exhibited temperature-induced expression, possibly compensating for SmHTH deficiency under high temperatures to restore fertility. The homologs co-expressed with three transcription factors are likely intricately linked to this response. We propose a compensatory model demonstrating that low SmHTH expression at low temperatures disrupts key metabolic pathways, causing male sterility. Conversely, elevated expression of homologous genes and transcription factors (TFs) at higher temperatures compensates for the loss of SmHTH function, thereby restoring fertility. The findings of this research not only deepen the theoretical understanding of plant male sterility mechanisms but also provide valuable resources for developing stress-resilient vegetable varieties through modern breeding techniques.