Analysis of gene expression changes and key factor functions in <i>Agrobacterium</i>-mediated genetic transformation in <i>Brassica campestris</i> ssp. <i>chinensis</i>

This study focused on the <italic>Agrobacterium</italic>-mediated genetic transformation of non-heading Chinese cabbage. Through transcriptome analysis, the functions of differentially expressed genes (DEGs) after <italic>Agrobacterium</italic> infection, changes in related metabolic pathways, and the potential roles of defensin-like protein 2 (DEFL2) and callus-specific genes were revealed. Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that <italic>Agrobacterium</italic> infection affected the expression of genes related to photosynthesis, metabolic pathways, plant-pathogen interactions, and signal transduction in non-heading Chinese cabbage. Alterations in photosynthesis-related gene expression influenced the efficiency of light energy capture and conversion. Changes in metabolic pathways were involved in energy supply, material synthesis, and secondary metabolite production. The plant activated defense responses to resist <italic>Agrobacterium</italic> invasion. Callus-specific genes might improve the infection efficiency of <italic>Agrobacterium</italic>, and DEFL2 might play important roles in plant defense and growth and development, although the specific mechanisms remain to be further investigated. This study provides a theoretical basis for the genetic improvement of non-heading Chinese cabbage and contributes to optimizing its genetic transformation system. However, in-depth research is still needed in aspects such as gene function verification, the regulatory mechanisms of signaling pathways, and the impacts of genomic changes.