Expression analysis of genes related to abscisic acid biosynthesis and signaling in response to flooding stress in sweetpotato

Flooding is detrimental to most agricultural crops. Sweetpotato, a root crop, has relatively strong resistance to drought and high temperature but is sensitive to flooding, which significantly reduces its commercial value and yield. Transcriptome analyses of flooding-tolerant and flooding-sensitive sweetpotato cultivars indicate that genes associated with the metabolism of various plant hormones, including abscisic acid (ABA), are involved in flooding stress tolerance. Although sweetpotato cultivars are classified as either sensitive or tolerant to flooding, the role of ABA metabolism and signaling in flooding resistance has not yet been elucidated. Therefore, in this study, we characterized the expression patterns of genes related to ABA metabolism and signaling in the leaves of two sweetpotato cultivars under flooding stress. NCED genes, associated with ABA biosynthesis, showed higher expression levels in the flooding-tolerant cultivar than in the flooding-sensitive cultivar. In contrast, CYP707A genes, involved in ABA catabolism, were significantly upregulated in the flooding-sensitive cultivar compared with the flooding-tolerant cultivar. Moreover, ABA signaling genes, encoding the PYR receptor and ABI5 transcription factor, were downregulated in the flooding-tolerant cultivar. These results suggest that genes involved in ABA metabolism and signaling play important roles in response to flooding stress in sweetpotato.