Dehydrins are intrinsically disordered proteins that play central roles in cryoprotection and osmotic stress tolerance in plants. In this study, we investigated orthologous KS dehydrin promoters from the Arctic Oxytropis arctobia (Fabaceae) and the temperate O. splendens using reporter gene constructs to evaluate transcriptional responses under abiotic stress conditions in transgenic Lotus japonicus. Reporter gene assays in freezeand heat-exposed L. japonicus plantlets showed that a specific region of the O. splendens promoter functions as a repressor, while both promoters contain temperature-responsive cis-elements. In parallel, we sequenced and analyzed the nuclear genomes of O. arctobia and O. splendens, focusing on identifying KS dehydrin orthologs and their regulatory regions. This revealed that the intron in the 3′ UTR is highly conserved between three Oxytropis species and in close relatives, which may contribute to post-transcriptional regulation and adaptation to harsh environments.Together, these results demonstrate cis-regulatory divergence in dehydrin promoters and provide new insights into the molecular mechanisms and evolutionary trajectories of cold adaptation in Oxytropis.
Tavares et al. (Wed,) studied this question.