Genome-Wide Identification and Functional Analysis of the AP2/ERF Transcription Factor Family in Citrus Rootstock under Waterlogging Stress

Citrus plants are sensitive to waterlogging, and the roots are the first plant organ affected by hypoxic stress. The (APETALA2/ethylene-responsive element binding factors) can modulate plant growth and development. However, the information on genes in citrus rootstock and their involvement in waterlogging conditions is limited. Previously, a rootstock cultivar, cv. Pujiang Xiangcheng was found to be highly tolerant to waterlogging stress. In this study, a total of 119 members were identified in the genome. Conserved motif and gene structure analyses indicated the evolutionary conservation of . Syntenic gene analysis revealed 22 collinearity pairs among the 119 . The expression profiles under waterlogging stress showed differential expression of , of which, was highly expressed in both root and leaf. Furthermore, the heterologous expression of significantly enhanced the tolerance of transgenic tobacco to waterlogging stress. The overexpression of decreased the oxidative damage in the transgenic plants by reducing the H O and MDA contents and increasing the antioxidant enzyme activities in the root and leaf. Overall, the current study provided basic information on the AP2/ERF family in the citrus rootstock and uncovered their potential function in positively regulating the waterlogging stress response.