Phenotypic and comparative transcriptomic analyses of resistant and susceptible germplasm reveal the putative resistance mechanisms of wheat to fusarium crown rot

Fusarium crown rot (FCR), primarily caused by Fusarium pseudograminearum, has emerged as a globally significant disease severely threatening the stability of wheat production. Breeding FCR-resistant germplasms and clarifying the underlying resistance mechanisms are critical prerequisites for effective disease management. In this study, to generate genotypes with enhanced FCR resistance, an EMS-mutagenized population was developed from AK58, and a germplasm X413 with stably moderate resistance to FCR at both the seedling and adult stages was identified. Phenotypic analysis showed that X413 exhibited stronger ability to inhibit the expansion and mycelial growth of F. pseudograminearum. Transcriptome (RNA-seq) comparison with highly susceptible X73 revealed that X413 had fewer differentially expressed genes (DEGs) after pathogen infection, with its specific DEGs significantly enriched in resistance-related pathways such as “lignin metabolic process” and “phenylpropanoid biosynthesis”. In contrast, X73 had more DEGs, and genes related to growth and development including those for DNA replication and post-replication repair were significantly downregulated, consistent with its more obvious plant height reduction after pathogen infection. Weighted gene co-expression network analysis (WGCNA) identified hub genes highly expressed in X413, including ubiquitin-related genes, kinase genes, and three germin-like protein genes (with SOD activity involved in hydrogen peroxide production). Physiological assays confirmed that X413 had significantly higher hydrogen peroxide content and SOD activity than X73. Collectively, FCR resistance in X413 may be associated with efficient activation of disease resistance pathways and balanced growth-defense metabolism. This germplasm could serve as a valuable resistance source to support wheat breeding for FCR resistance, and the mechanistic insights obtained may also lay a solid theoretical foundation for the mining and utilization of resistance genes.