Evolutionary and Expression Analysis Provides Evidence for the Plant Glutamate-like Receptors Family is Involved in Woody Growth-related Function.

Jianqing Chen,Shaoling Zhang,Yinghui Jing,Leiting Li,Hongsheng Zhou,Peng Wang,Juyou Wu,Xinyue Zhang

doi:10.1038/srep32013

Jianqing Chen, Shaoling Zhang + Show 6 more

Open Access

https://doi.org/10.1038/srep32013

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Abstract

Glutamate-like receptors (GLRs) is a highly conserved family of ligand-gated ion channels, which have been associated with various physiological and developmental processes. Here, we investigated the evolutionary pattern of GLRs in plants. We observed that tandem duplications occupied the largest proportion of the plant GLR gene family expansion. Based on a phylogenetic tree, we suggested a new subfamily, GLR4, which is widespread in angiosperm but absence on Brassicales. Meanwhile, because GLR1 and GLR2 subfamilies were potential sister clades, we combined them into the GLR1&2 subfamily. A comparative analysis of plant GLR subfamilies revealed that selective forces shaped the GLR1&2 repertoires in the stems of eudicotyledons with distinct functional preferences. Moreover, GLR1&2 formed a species-specific highwoody-expanded subfamily, with preferential expression in the cambial-enriched and shoot apical meristem fractions of the highwood species. Together, these findings lay the foundation for evolutionary analysis of plant GLRs over the entire plant timescale and identified unique targets for manipulating the woody-growth behaviours of plant GLRs.

Highlights

Despite the classification, plant Glutamate-like receptors (GLRs) as predicted ligand-gated ion channels share the basic structures of the channel-forming domains and ligand-binding sites[2]
Phylogenetic analysis suggested that analogous to Arabidopsis, most Rosaceae GLRs were divided into three traditional phylogenetic clades (GLR1, GLR2 and GLR3)
The residues that determine the selective transduction of cations were highly uniform among Rosaceae and Arabidopsis GLRs included GLR4 subfamily (Fig. S2)

Summary

Introduction

Plant GLRs as predicted ligand-gated ion channels share the basic structures of the channel-forming domains and ligand-binding sites[2]. Applying exogenous glutathione to Arabidopsis leaves triggered a transient rise in cytosolic Ca2+ concentration, which is highly sensitive to GLR antagonists, and was impaired in loss-of-function atglr3.3 mutants[11] These mutants showed enhanced susceptibility to bacterial pathogens, lower expression of pathogen-induced defence marker genes and similar phenotype to the glutathione biosynthesis defective mutant pad[211]. Mutations in several GLR3 genes (3.2, 3.3 and 3.6) alleviated wound-induced surface potential changes and correlated with jasmonate-response gene expression, which was more attenuated in a glr3.3 glr3.6 double mutant[22] This suggests that electrical impulses act as intracellular signals and that plant GLRs are potent regulators in this long-distance communication in wound-induced defence responses. Plant GLRs, as extracellular amino acid sensors, play fundamental roles in regulating various biological processes Knowledge of this gene family is confined to Arabidopsis thaliana.

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