Identification of <i>Populus tomentosa</i> OSCA Gene Family and Its Expression Analysis under Salt Stress

OSCA  (Hyperosmdality-gate calcium-permeable channels) is a calcium-permeable cation channel protein. By participating in sensing changes in extracellular osmotic potential, it induces an increase in Ca 2+  concentration, regulates osmotic potential, and plays an important role in hypertonic stress induction. However, there are few studies on the  OSCA  genes of poplar. In this study, 16  OSCA  genes sequences were identified from  Populus tomentosa  genome, and renamed them according to their distribution on the chromosomes. Based on phylogenetic tree analysis, the  PtOSCAs  genes were divided into 4 groups, and the  OSCA  genes in each group had similar gene structures. Two repetitive events were identified between poplar OSCA family genes, one tandem repetitive event involving 3 genes and a fragment repetitive event involving 2 genes, and the Ka/Ks value of each pair of genes was below 1. Therefore, it can be seen that the OSCA family genes of poplar have a purification effect during evolution. By analyzing the expression of  PtOSCAs  gene under low and high concentration salt stress, it is found that there are the following three types: Type I, where the expression level increases under both low and high concentration salt stress; Type II, at low and high concentration salt stress, the expression level decreased under high concentration salt stress; Type Ⅲ, the expression level showed an upward trend under low concentration salt stress, but the expression level showed a downward trend under high concentration salt stress. This study provides a reference for the functional analysis of  PtOSCAs  gene and the genetic improvement of poplar.