Genome-wide identification and expression analysis of E3 ubiquitin-protein ligase U-box family in Physcomitrium patens

The U-box family encodes E3 ubiquitin ligase, which can specifically recognize the substrate and thus regulate the process of protein modification and degradation. In order to identificate the members of the Physcomitrium patens U-box family and to analyze their gene expression regularities, their physicochemical characteristics, evolutionary relationship, cis-acting element, tissue expression patterns and stress response were analyzed based on the whole sequencing data of P. patens through bioinformatics technology. The results were as follows:(1)A total of 31 U-box family members were identified in the whole genome of P. patens and were unevenly distributed on 14 chromosomes; their molecular weight sizes ranged from 37.75-117.49 kDa, and their isoelectric points ranged from 5.32-8.55.(2)The evolutionary tree showed that the U-box family members of P. patens were distributed in subfamilies I-IX, among which subfamily Ⅶ contained the largest number of members, with a total of 11 members accounting for about 36.67%. This indicated that P. patens was highly conserved and functionally diversified in the historical evolutionary process.(3)Promoter analysis yielded that P. patens U-box family members had elements that binded several hormones including GA and ABA.(4)Tissue expression analysis yielded that P. patens U-box family members was abundantly expressed mainly in the chloroplast, axoplast, and sporophyte S3 periods.(5)After simulated drought treatment with ABA, mannitol and saturated LiCl, it was found that the proposed stems of gametophytes were yellowed and the expression of PpPUB21 was significantly induced. It is hypothesized that the P. patens U-box family members plays an important role in growth and development and in response to adversity stress, and these findings provide a reference for further research on the U-box gene of P. patens.