Genome-wide identification and expression analysis of the IQD gene family in moso bamboo (Phyllostachys edulis).

Min Wu,Yan Xiang,Huanlong Liu,Dongyue Zhu,Yuan Li,Danmei Chen

doi:10.1038/srep24520

Abstract

Members of the plant-specific IQ67-domain (IQD) protein family are involved in various aspects of normal plant growth and developmental processes as well as basal defence response. Although hundreds of IQD proteins have been identified, only a small number of IQDs have been functionally characterized. Moreover, no systematic study has been performed on moso bamboo. In this study, we performed for the first time a genome-wide identification and expression analysis of the IQD gene family in moso bamboo. We identified 29 non-redundant PeIQD encoding genes. Analysis of the evolutionary patterns and divergence revealed that the IQD genes underwent a large-scale event around 12 million years ago and the division times of IQD family genes between moso bamboo and rice, and, between moso bamboo and Brachypodium, were found to be 20–35 MYA and 25–40 MYA, respectively. We surveyed the putative promoter regions of the PeIQD genes, which showed that largely stress-related cis-elements existed in these genes. The expression profiles of the IQD genes shed light on their functional divergence. Additionally, a yeast two-hybrid assay proved that PeIQD8 can interact with PeCaM2 and that IQ or I in the IQ motif is required for PeIQD8 to combine with CaM2.

Highlights

Ca2+ is a pivotal cytosolic second messenger, which plays a prominent role in many essential biological processes in plants
29 IQD genes were identified, and all of these predicted that IQD proteins had a typical “IQ calmodulin-binding motif ” domain (PF00612) which is a major calcium (Ca2+) regulator
The open reading frame (ORF) length ranged from 573 bp (IQD6) to 2823 bp (IQD17), the molecular weight (MW) from 20417.05 (IQD6) to 105765.41 (IQD17) Da, and the pI from 5.02 (IQD5) to 11.12 (IQD9)

Summary

Introduction

Ca2+ is a pivotal cytosolic second messenger, which plays a prominent role in many essential biological processes in plants. CIPKs most likely substitute for CBLs, which have no enzymatic activity, to receive and transmit the Ca2+ signals, while calmodulins (CaMs) and CBL sensor proteins have no catalytic activity on their own and are sometimes referred to as “Ca2+ sensor relays”, in contrast to CDPK proteins, which are considered “Ca2+ sensor responders” The encoded IQD proteins contain a plant-specific domain of 67 conserved amino acid residues, referred to as the “IQ67 domain”. The first representative CaM target proteins have been identified in Arabidopsis thaliana and rice, and encoded 33 and 29 IQD1-like genes, respectively, were identified within the IQ67 domain[6] They have been identified in other species (soybean, Brachypodium distachyon, Populus trichocarpa, tomato and others). The results of this study provide a biological reference for further elucidating the role of IQDs in plants

Methods

Results

Discussion

Conclusion