Comprehensive Genome-Wide Identification and Characterization of the AP2 Subfamily in Beta vulgaris L. in Response to Exogenous Abscisic Acid

APETALA2 (AP2) belongs to transcription factor (TF) families, with crucial roles in regulating plant growth, development, and stress responses. In order to explore the characteristics of sugar beet ( Beta vulgaris L.) AP2s ( BvAP2s ) in response to drought stress hormone abscisic acid (ABA), genome-wide identification, and the phylogeny, gene structure and promoter precursor analysis of the BvAP2s were employed to predict their potential functions. It is shown that there are a total of 13 BvAP2 genes in the Beta vulgaris . Based on the primary amino acid sequence, the BvAP2s can be further subdivided into euAP2, euANT and basalANT. In addition, cis-acting element analysis showed that BvAP2s contained several abiotic stress-related elements, including those associated with ABA and drought stress. Roots are the first to perceive stress signals, and ABA-treated beetroot transcriptome and downstream gene prediction of BvAP2s revealed that BVRB_4g074790 , BVRB_6g128480 and BVRB_7g179610 may play an important role involved in ABA signaling pathways during the stress response by regulating downstream GRAM genes, LEAs and U-boxes. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) further confirmed the downregulation of these three BvAP2s in response to ABA induction in sugar beet roots. These findings provide a basis for future utilization of BvAP2s in developing drought-tolerant Beta vulgaris varieties.