Transcriptome Analysis of Cabbage Near-Isogenic Lines Reveals the Involvement of the Plant Defensin Gene PDF1.2 in Fusarium Wilt Resistance

Fusarium wilt of cabbage (Brassica oleracea var. capitata), caused by Fusarium oxysporum f. sp. conglutinans (Foc), poses a significant threat to global cabbage production. Although resistance screening and the initial cloning of resistance genes in cabbage have been previously reported, the specific molecular mechanisms underlying cabbage resistance to Foc remain largely unknown. To elucidate the underlying mechanisms, we performed RNA sequencing analysis on a near-isogenic resistant line YR01_20 and a susceptible NIL line S01_20 by comparing both Foc-inoculated and mock-inoculated conditions. A total of 508.6 million sequencing raw reads (76.8 Gb data volume) were generated across all samples. Bioinformatics analysis of differentially expressed genes (DEGs) between S01_20 and YR01_20 revealed significant enrichment in plant hormone signaling and mitogen-activated protein kinase (MAPK) pathways. Notably, BolC06g030650.2J, encoding the plant defensin protein PDF1.2, was significantly upregulated in both pathways. Real-time quantitative PCR (RT-qPCR) analysis confirmed that PDF1.2 was significantly upregulated in the resistant line at 12 h post-inoculation and remained elevated for up to 144 h. Furthermore, transgenic cabbage overexpressing PDF1.2 exhibited significantly enhanced resistance to Foc. Taken together, these findings advance our understanding of the molecular mechanisms governing cabbage resistance to Fusarium wilt and identify PDF1.2 as a genetic target for breeding Foc-resistant cabbage cultivars through molecular approaches.