BpTCP7 gene from Betula platyphylla regulates tolerance to salt and drought stress through multiple hormone pathways

Key message Overexpression of BpTCP7 gene leaded to improved scavenging reactive oxygen species (ROS) in drought and salinity treatment through multiple hormone pathways in Betula platyphylla. TEOSINTE-LIKE1, CYCLOIDEA, and PROLIFERATING CELL FACTOR1 (TCP) genes are plant-specific transcription factors, which play important roles in plant growth and development. The function of CIN subclass of the TCP gene family has not been well revealed. In this investigation, five CIN subfamily members were identified in Betula platyphylla, all of which contained the conservative domains associated with the CIN subclass. Most of the genes were involved in the development of leaves, apical buds, and male inflorescences, especially the BpTCP7 gene. The results of GUS activity assays driven by BpTCP7 promoters confirmed these conclusions. The analysis of the BpTCP7 promoter also showed that the gene was induced by salt and drought stresses, and multiple hormones. Through Agrobacterium-mediated genetic transformation, we obtained four independent birch lines with over-expression of BpTCP7. Moreover, physiological and enzymatic analysis of transgenic lines under salt and drought stress showed that the scavenging effect of reactive oxygen species (ROS) of transgenic lines was improved. Our results provide useful information for revealing the functions of CIN subclasses in the growth and development of B. platyphylla and their applications in scavenging of ROS.