Physcomitrium patens: A Model for Studying the Evolution of Proteins with Lectin Domains in Plants

Abstract

Moss Physcomitrium (formerly Physcomitrella) patens (Hedw.) Mitt. is a seedless vascular plant with a deciphered genome, a representative of the most ancient living taxa of land plants, and a convenient model for studying the evolutionary development of plants. In order to study the formation and functions of carbohydrate-binding proteins in plants during evolution, a genome-wide screening of genes encoding proteins with lectin domains in the P. patens genome was carried out, and their expression in various cells and tissues of moss was analyzed. We identified 141 genes encoding proteins from 15 families, the set and number of representatives of which differed significantly from the earlier analyzed angiosperms. In P. patens, some of the proteins with lectin domains had a specific domain architecture absent in higher seed plants. Clustering of genes according to their level of expression in various tissues of moss showed three patterns of expression of genes for proteins with lectin domains, of which the third cluster, presented in cells with a tip growth type (in caulonema, chloronema, and moss rhizoids), was characterized by the largest number of actively expressed genes. The results obtained support the idea of the early appearance of genes encoding lectins in plants and the further expansion of families of proteins with lectin domains with increasing complexity of plant organization.