Jasmonic acids (JAs), as endogenous plant hormones, play a crucial role in the plant response to salt stress. 12-oxophytodienoate reductase (OPR), a key enzyme in JA biosynthesis, remains poorly understood in terms of its expression regulation. To identify transcription factors involved in regulating IbOPR2 expression, this study used the salt-tolerant sweetpotato cultivar ‘Haida 7791’ to clone the promoter sequence of the IbOPR2 gene. Bioinformatics analysis revealed various cis-acting elements, and transcriptional activation assays confirmed promoter activity. Yeast one-hybrid (Y1H) screening was conducted to identify transcription factors interacting with the promoter, and point-to-point Y1H assays were used to validate specific binding. A 1964 bp promoter sequence upstream of IbOPR2 was successfully cloned, containing recognition motifs such as MYBHv1, MYB, and WRKY, along with stress-responsive elements (MYB, MYC) and MeJA-responsive elements, indicating strong transcriptional activation potential. Five candidate transcription factors—PHL7, ZFP16, SKIP11, TGA2, and ERF2—were identified using MYC and MeJA response elements as bait in Y1H assays. Follow-up point-to-point verification confirmed that IbPHL7, IbZFP16, and IbSKIP11 specifically bind to the IbOPR2 promoter. Dual-luciferase reporter assays further demonstrated that these three transcription factors could activate the IbOPR2 promoter. Moreover, qRT-PCR analysis showed that the expression of IbPHL7, IbZFP16, and IbSKIP11 is responsive to salt stress in sweetpotato. Taken together, these results suggest that these transcription factors may function as upstream regulators of IbOPR2, modulating its expression under salt stress conditions. This study represents the first identification of transcriptional regulators of sweetpotato IbOPR2, providing a foundation for further investigation into its regulatory mechanisms in response to salt stress.
Wang et al. (Wed,) studied this question.