Genome-wide analysis of LSH genes reveals evolutionary patterns in Rosaceae and a positive role for MdLSH10b in adventitious root formation

The plant-specific LIGHT-SENSITIVE SHORT HYPOCOTYL (LSH) genes are integral to the development of plant organs. However, the evolution and function of LSH genes in Rosaceae remain poorly understood. Here, 60 LSH genes were systematically identified across the genomes of six Rosaceae species. Phylogenetic analysis grouped these LSH genes into four distinct clades. The analysis of LSH gene family duplications revealed that whole-genome duplication (WGD) and transposed duplication (TRD) primarily drive the expansion of the LSH gene family in Rosaceae species. In apple, 18 MdLSH gene pairs generated through WGD have undergone purifying selection. Further transcriptome analysis demonstrated that MdLSH genes exhibit distinct expression patterns across different tissues. Among them, MdLSH10b was significantly induced at the induction stage of adventitious roots. The integration of transcriptome and promoter analyses indicated that MdLSH10b potentially regulates the expression of MdWOX4a. Yeast one-hybrid assays (Y1H) and β-glucuronidase (GUS) activity analyses demonstrated that MdLSH10b transcriptionally activates MdWOX4a. Notably, transient overexpression of MdLSH10b in apple resulted in an increased rate of adventitious root induction. In conclusion, this study suggests that MdLSH10b may promote adventitious root formation by transcriptionally activating MdWOX4a and provides new genetic resources for further functional investigations on MdLSH genes in apple development.