PbrMYB31 mejora la tolerancia al estrés abiótico promoviendo la biosíntesis de suberina en Arabidopsis

Plants, being immobile, are exposed to fluctuating environmental stresses and have therefore evolved sophisticated adaptive strategies. Transcription factors are central to these responses, integrating external signals with the regulation of stress-responsive genes. Among them, MYB proteins represent one of the largest and most intensively studied families, widely involved in secondary metabolite biosynthesis, including anthocyanins, suberin, and lignin. Despite the identification of many MYB members in abiotic stress responses, their precise regulatory mechanisms remain poorly understood. In this study, we characterized the PbrMYB31 gene from Pyrus bretschneideri, which encodes an R2R3-type MYB transcription factor. Overexpression of PbrMYB31 in transgenic Arabidopsis thaliana improved plant tolerance to salt and cold stress and enhanced ABA-mediated adaptive responses under abscisic acid (ABA) treatment. Mechanistically, PbrMYB31 was shown to directly bind to the promoter of the fatty acid metabolism-related gene CYP86A1, thereby promoting suberin biosynthesis. Consistent with these findings, PbrMYB31 enhances stress adaptation by reinforcing endodermal cell suberization through direct transcriptional activation of CYP86A1. Collectively, our results demonstrate that PbrMYB31 functions as a central regulator of the PbrMYB31- CYP86A1-suberin-ABA axis, thereby strengthening structural barriers and improving abiotic stress tolerance in plants, providing a mechanistic framework for understanding suberin-associated abiotic stress tolerance in plants.