Identification of the DOG1 Gene Family in Cultivated Peanut and Negative Regulation of Ralstonia solanacearum Infection by AhDOG1-L4

Bacterial wilt, caused by Ralstonia solanacearum, is a devastating soilborne disease often referred to as plant cancer. It threatens hundreds of species of plants and causes losses in yield and a deterioration in the quality of infected plants. Delay of Germination 1 (DOG1) plays vital roles in plant growth, development, and abiotic and biotic stress responses. However, the functions of DOG1 in biotic stress remain unexplored in cultivated peanut (Arachis hypogaea L.). In this study, we systematically identified and characterized the AhDOG1 gene family in peanut using bioinformatics approaches and used transgenic experiments to functionally investigate AhDOG1-L4 in response to infection with Ralstonia solanacearum. A total of 37 AhDOG1 genes were identified in the peanut genome and classified into six subfamilies based on their phylogenic relationship. Their patterns of expression were studied and showed that AhDOG1-L4 is highly expressed in roots, root tips, rhizomes, nodules, stems, stem tips, cytoledons, leaves, florescences, and pegs. Importantly, among these tissues, the root tips exhibit the highest expression level of AhDOG1-L4. The heterologous overexpression of AhDOG1-L4 significantly reduced the tolerance of transgenic Arabidopsis thaliana to Ralstonia solanacearum infection. Moreover, AhDOG1-L4 may participate in plant defense against pathogens by modulating the expression of genes associated with defense signaling networks. Functional characterization revealed that heterologous overexpression of AhDOG1-L4 in Arabidopsis significantly increased susceptibility to Ralstonia solanacearum by suppressing the expression of defense-related genes, demonstrating that AhDOG1-L4 functions as a plant negative regulator of bacterial wilt resistance. To the best of our knowledge, this is the first study into the roles of AhDOG1 genes in the responses to stress in peanut plants.