Evolution of RGF/GLV/CLEL Peptide Hormones and Their Roles in Land Plant Growth and Regulation

Abstract

Rooting is a key innovation during plant terrestrialization. RGFs/GLVs/CLELs are a family of secreted peptides, playing key roles in root stem cell niche maintenance and pattern formation. The origin of this peptide family is not well characterized. RGFs and their receptor genes, RGIs, were investigated comprehensively using phylogenetic and genetic analyses. We identified 203 RGF genes from 24 plant species, representing a variety of land plant lineages. We found that the RGF genes originate from land plants and expand via multiple duplication events. The lineage-specific RGF duplicates are retained due to their regulatory divergence, while a majority of RGFs experienced strong purifying selection in most land plants. Functional analysis indicated that RGFs and their receptor genes, RGIs, isolated from liverwort, tomato, and maize possess similar biological functions with their counterparts from Arabidopsis in root development. RGFs and RGIs are likely coevolved in land plants. Our studies shed light on the origin and functional conservation of this important peptide family in plant root development.

Molecular Mechanisms of Regulation of Root Development by Plant Peptides

“…RGFs also play a critical role in the regulation of plant gravitropism [ 116 , 117 ], the formation of lateral roots and root hairs [ 118 , 119 , 120 ], and are sensitive to phosphate deprivation [ 82 ]. The results of a study using synthetic RGF peptides (DYAEPDTHPPESN, YSPAKRKPPIHN, DYKSPRHHPPRHN and, DYHSVHRHPPTHN) [ 121 ] showed that all synthetic peptides, both tyrosine sulfated and proline hydroxylated, can cause wild-type root sway in seedlings. Gravistimulation assays have shown that these peptides influence the gravitropic response of the root.…”