Integrated Analysis of Transcriptome and Metabolome Reveals Differential Responses to Infection in Cabbage ( var. ).

Black spot, caused by (), poses a serious threat to crucifer production, and knowledge of how plants respond to infection is essential for black spot management. In the current study, combined transcriptomic and metabolic analysis was employed to investigate the response to infection in two cabbage ( var. ) genotypes, Bo257 (resistant to ) and Bo190 (susceptible to ). A total of 1100 and 7490 differentially expressed genes were identified in Bo257 (R_mock vs. R_) and Bo190 (S_mock vs. S_), respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that "metabolic pathways", "biosynthesis of secondary metabolites", and "glucosinolate biosynthesis" were the top three enriched KEGG pathways in Bo257, while "metabolic pathways", "biosynthesis of secondary metabolites", and "carbon metabolism" were the top three enriched KEGG pathways in Bo190. Further analysis showed that genes involved in extracellular reactive oxygen species (ROS) production, jasmonic acid signaling pathway, and indolic glucosinolate biosynthesis pathway were differentially expressed in response to infection. Notably, when infected with , genes involved in extracellular ROS production were largely unchanged in Bo257, whereas most of these genes were upregulated in Bo190. Metabolic profiling revealed 24 and 56 differentially accumulated metabolites in Bo257 and Bo190, respectively, with the majority being primary metabolites. Further analysis revealed that dramatic accumulation of succinate was observed in Bo257 and Bo190, which may provide energy for resistance responses against infection via the tricarboxylic acid cycle pathway. Collectively, this study provides comprehensive insights into the -cabbage interactions and helps uncover targets for breeding -resistant varieties in cabbage.