Genome-wide identification of MYB gene family and functional characterization of PpMYB2 on cold tolerance in Pennisetum purpureum

With the exacerbation of global climate change, low-temperature stress has become a severe environmental challenge worldwide. Cultivation of the high-biomass tropical forage grass Pennisetum purpureum is severely constrained by low-temperature stress. In this study, we performed the first genome-wide identification of the MYB transcription factor family in P. purpureum and characterized the function of PpMYB2. Transcriptional profiling revealed spatiotemporal expression patterns of PpMYB2, PpMYB4, and PpMYB6 in response to cold treatment. Heterologous expression of PpMYB2 in yeast significantly improved growth under low-temperature conditions. Transgenic Arabidopsis thaliana lines overexpressing PpMYB2 exhibited markedly enhanced cold tolerance, showing lower electrolyte leakage, reduced ROS accumulation, higher chlorophyll content, and greater relative water content than wild-type plants. These results demonstrate that PpMYB2 positively regulates cold tolerance by alleviating membrane damage and oxidative stress. The results advance the understanding of regulatory mechanisms underlying plant cold tolerance and establish a molecular framework for breeding cold-resistant crops.