The overexpression of the BpTCP20 gene enhances cell proliferation and improves tolerance to drought and salt stress in Betula platyphylla

Plants are often subjected to adverse environmental conditions during their growth and development. In order to survive and adapt to their surroundings, plants have evolved various signal transduction pathways and complex physiological and biochemical mechanisms to respond to stress. TCP transcription factors constitute a class of plant-specific transcriptional regulators that govern plant morphology and structure, contributing to the evolution of plant diversity. They are also implicated in various vital biological processes, including plant gametophyte development, circadian rhythms, and hormone signaling. However, the precise underlying physiological mechanisms remain largely unexplored. In this study, we discovered that TCP transcription factor family proteins exhibit remarkable conservation, with an impressive 98 % homology observed between BpTCP20 and AtTCP20. The BpTCP20 gene plays a crucial role in leaf development, as well as in mediating responses to various hormonal and abiotic stress factors. Notably, Betula platyphylla plants overexpressing BpTCP20 displayed increased seedling height, ground diameter, and leaf area compared with their wild-type counterparts, leading to a significant enhancement in their drought and salt tolerance. Further investigations demonstrated that, under conditions of drought and salt stress, Betula platyphylla plants overexpressing BpTCP20 exhibited lower drought indices, salt indices, hydrogen peroxide levels, and malondialdehyde contents compared with wild-type plants. Conversely, chlorophyll and peroxidase contents increased significantly, along with the upregulation of peroxidase and superoxide dismutase related genes. These findings strongly indicate that BpTCP20 plays a positive regulatory role in enhancing drought and salt tolerance in Betula platyphylla. Utilizing RNA sequencing, we identified pathways and transcription factors associated with plant growth and development, as well as drought and salt tolerance. Furthermore, through Yeast one-hybrid assays, we uncovered interactions between BpTCP20 and BpMYB8 and BpIAA5. This study sheds light on the crucial function of BpTCP20 in the regulation of growth and development in Betula platyphylla strains, as well as their response to drought and salt stress. It also underscores the potential of BpTCP20 as a candidate gene for enhancing drought and salt tolerance in plants.