Multi-Time Point Transcriptome Analysis and Functional Validation Revealed Negatively Regulates Black Rot Resistance in Cabbage.

4-coumarate-CoA ligase (4CL) plays a crucial role in the phenylpropanoid metabolic pathway and is a key enzyme involved in plant growth and stress responses. Black rot, caused by pv. () is a major bacterial disease affecting the production of global cruciferous crop-like cabbage ( var. ). However, the role of genes in cabbage resistance to black rot remains unclear. In this study, transcriptome sequencing was conducted using resistant cabbage MY and susceptible cabbage LY at 0, 6, 24, and 48 h post-inoculation. KEGG analysis identified the enrichment of the phenylpropanoid biosynthesis pathway, and significant expression changes of genes were determined through the expression heat map. Further genome-wide analysis revealed 43 gene family members on the cabbage genome distributed across nine chromosomes. Gene structure and protein motif analysis revealed similarities in motifs within the same evolutionary branch, but variations in gene structure. A combination of gene expression profiles and differentially expressed genes (DEGs) from the transcriptome identified as a key gene for further study. Inoculation of overexpressed T generation stably expressed cabbage seedlings demonstrated significantly larger lesion areas compared to wild type cabbage, indicating that negatively regulates resistance to black rot in cabbage. The analysis of multi-time point transcriptomes in cabbage and the functional study of the gene family enhance our understanding of the mechanisms underlying plant disease resistance. This provides compelling evidence and experimental support for elucidating the mechanisms of black rot resistance in cabbage.