Characterization and evolutionary diversification of the phospholipase D gene family in mosses

Plant phospholipase D (PLD) exerts important roles in various biological processes, such as intracellular signaling and morphological development. Our knowledge about early land plant is still underdeveloped. In this study, we identified 84 genes in six mosses, i.e., , , , , , and . These were classified into four clades (I-IV). We showed that underwent rapid expansion in mosses A total of six conserved domains and two core HKD motifs were detected. Structure analysis uncovered that the moss from within a clade generally exhibited similar exon-intron organization. -elements prediction and expression analyses indicated that had key roles in stress responsiveness and plant development. Particularly, about half of the (e.g., , , and ) were differentially expressed under biotic and abiotic stresses. We also determined the expression pattern of genes in various tissues and at different stages of development. Although the moss, clubmoss, liverwort, and fern evolved largely under functional constraints, we found episodic positive selection in the moss , e.g., and . We infer that the evolutionary force acting on the may have facilitated moss colonization of land. Our work provides valuable insights into the diversification of moss genes, and can be used for future studies of their functions.