Genome-Wide Identification, Expression Analysis and Functional Study of Genes in Chinese Cabbage ( L. ssp. ).

Background: DELLA protein is a crucial factor which played pivotal roles in regulating numerous intriguing biological processes in plant development and abiotic stress responses. However, little is known about the function and information of DELLA protein in Chinese cabbage.

Methods: Using 5 gene sequences in as probes, 5 genes in Chinese cabbage were identified by Blast search in Chinese cabbage database (Brassica database (BRAD)). The National Center for Biotechnology Information (NCBI), ExPaSy, SWISS-MODEL, DNAMAN, MEGA 11, PlantCARE were used to identify and analyze the gene family of Chinese cabbage. Gene expression was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The function of was verified by overexpression and phenotypic analysis of and yeast hybrid.

Results: In this study, 5 homologous to were identified and cloned based on the Brassica database, namely, , , , and . All BraDELLAs contain the DELLA, TVHYNP, and GRAS conserved domains. Cis-element analysis revealed that the promoter regions of these 5 genes all contain light-responsive elements, TCT motif, I-box, G-box, and box 4, which are associated with GA signaling. Transcriptome analysis results proved that the expression of , , and in Y2 at different growth stages were lower than them in Y7, which is consistent with the phenotype that Y7 exhibited stronger stress tolerance than Y2. It is worth emphasizing that even through the overexpression of in resulted in smaller leaf size and lower fresh weight compared to the wild type (WT) Arabidopsis: Columbia, a stronger response to abiotic stresses was observed in . It indicated that can improve the stress resistance of plants by inhibiting their growth. Moreover, the yeast two-hybrid experiment confirmed that BraA10gRGL3-Y7 can interacted with BraA05gGID1a-Y7, BraA04gGID1b1, BraA09gGID1b3-Y2, and BraA06gGID1c, whereas BraA10gRGL3-Y2 cannot interact with any BraGID1.

Conclusions: Collectively, play important role in plant development and response to abiotic stress. The differences in amino acid sequences between BraA10gRGL3-Y2 and BraA10gRGL3-Y7 may result in variations in their protein binding sites, thus affecting their interaction with the BraGID1 family proteins. This systematic analysis lays the foundation for further study of the functional characteristics of genes of Chinese cabbage.