Identification of the BrC2DP gene family in Chinese Cabbage and functional analysis of the BrC2DP56 gene in drought stress

C2 domain-containing proteins (C2DPs) constitute a family of calcium-dependent regulators involved in membrane trafficking and signal transduction, playing critical roles in plant growth, development, and stress responses. However, this gene family has not yet been systematically characterized in Chinese cabbage. In this study, 157 BrC2DP members were identified and found to be unevenly distributed across 10 chromosomes, with notable gene clusters. Phylogenetic analysis classified them into 7 groups, and collinearity analysis revealed 112 duplicated gene pairs, indicating that segmental duplications contributed substantially to the expansion of this family. Notably, expression analysis under drought stress identified BrC2DP56 as a significantly up-regulated gene. Subcellular localization showed that BrC2DP56 was localized to the endoplasmic reticulum. Functional assays demonstrated that transient silencing of BrC2DP56 enhanced drought tolerance, whereas its overexpression increased susceptibility to drought, suggesting that BrC2DP56 negatively regulates drought stress responses in Chinese cabbage. This study provided a theoretical basis for exploring the drought response mechanism of the BrC2DP family.