Comprehensive Evolutionary Analysis of the SMXL Gene Family in Rosaceae: Further Insights into Its Origin, Expansion, Diversification, and Role in Regulating Pear Branching

genes constitute a conserved gene family that is ubiquitous in angiosperms and involved in regulating various plant processes, including branching, leaf elongation, and anthocyanin biosynthesis, but little is known about their molecular functions in pear branching. Here, we performed genome-wide identification and investigation of the genes in 16 angiosperms and analyzed their phylogenetics, structural features, conserved motifs, and expression patterns. In total, 121 genes were identified and were classified into four groups. The number of non-redundant genes in each species varied from 3 ( Baill.) to 18 ( Merr.) and revealed clear gene expansion events over evolutionary history. All the genes showed conserved structures, containing no more than two introns. Three-dimensional protein structure prediction revealed distinct structures between but similar structures within groups. A quantitative real-time PCR analysis revealed different expressions of 10 genes from pear branching induced by fruit-thinning treatment. Overall, our study provides a comprehensive investigation of genes in the Rosaceae family, especially pear. The results offer a reference for understanding the evolutionary history of genes and provide excellent candidates for studying fruit tree branching regulation, and in facilitating pear pruning and planting strategies.