KaMYB71 positively regulates drought tolerance in Krascheninnikovia arborescens.

Drought stress severely limits plant growth and crop productivity. Although wild species adapted to extreme environments represent valuable genetic resources for understanding stress tolerance mechanisms, their molecular basis remains largely unexplored. Here, KaMYB71, encoding an R2R3-MYB transcription factor, was identified from the desert shrub Krascheninnikovia arborescens through transcriptomic screening. KaMYB71 was predominantly expressed in roots and was rapidly induced by salt, osmotic stress, and abscisic acid (ABA). It encoded a nuclear-localized transcriptional activator. Overexpression of KaMYB71 in K. arborescens hairy roots significantly enhanced drought tolerance, with transgenic plants exhibiting higher Fv/Fm and proline content, elevated antioxidant enzyme activities, and reduced reactive oxygen species (ROS) and malondialdehyde (MDA) levels. Promoter analysis revealed multiple stress-responsive cis-elements in the KaMYB71 promoter. Screening of upstream transcription factors identified KaABF2, an osmotic stress-inducible bZIP protein, as a direct activator of the KaMYB71 promoter, establishing a KaABF2-KaMYB71 regulatory module. These findings identify KaMYB71 as a positive regulator of drought tolerance in K. arborescens and highlight the value of mining stress-adaptive genes from wild plant species.