Objective  To study the expansion and expression of the MAP65 gene family members by using Populus trichocarpa, a model forest plant, as research material.

Method  Using BLASTP to identify the members of PtMAP65 gene family based on Phytozome database, and using tools such as Prot-Param, Plant-mPLoc, LocTree3, Wolfsort, MAGA7.0, GSDS, MEME, MCScanX, TBtools, BioEdit Sequence Alignment Editor, DnaSP5 and plantCARE to analyze the physical and chemical properties, predict subcellular locations, construct a phylogenetic tree, draw a gene structure diagram, analyze conserved domains, gene duplication events and promoter elements; and analyze the expression of PtMAP65 gene family members in different tissues based on gene chip data.

Result  Nine MAP65 genes were identified by BLASTP comparison. Phylogenetic analysis showed that the plant MAP65 gene family can be divided into 5 groups, and each group had a similar gene structure and conserved domain. The results of collinearity analysis and Ka and Ks analysis of the P. trichocarpa genome indicated that there were six pairs of segmental duplication genes in the PtMAP65 gene family, and the duplication genes were subject to strong purification selection in the evolutionary process. Analysis of the expression data showed that PtMAP65 gene family members had different expression patterns in different tissues, suggesting their functional divergence. Cis-acting element analysis of the promoter showed that PtMAP65s promoter had more light response and hormone response elements than stress response, growth and development elements.

Conclusion  Segmental duplication is a main force driving the evolution and expansion of PtMAP65 gene family, and it is speculated that there has been functional divergence among the PtMAP65 gene family members.