Genome-Wide Identification of GRAS Gene Family and Their Responses to Abiotic Stress in Medicago sativa.

Han Zhang,Ming Sun,Xuemeng Wang,Rui Song,Xiqiang Liu,Shangang Jia,Peisheng Mao

doi:10.3390/ijms22147729

Han Zhang, Ming Sun + Show 5 more

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https://doi.org/10.3390/ijms22147729

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Abstract

Alfalfa (Medicago sativa) is a high-quality legume forage crop worldwide, and alfalfa production is often threatened by abiotic environmental stresses. GRAS proteins are important transcription factors that play a vital role in plant development, as well as in response to environmental stress. In this study, the availability of alfalfa genome “Zhongmu No.1” allowed us to identify 51 GRAS family members, i.e., MsGRAS. MsGRAS proteins could be classified into nine subgroups with distinct conserved domains, and tandem and segmental duplications were observed as an expansion strategy of this gene family. In RNA-Seq analysis, 14 MsGRAS genes were not expressed in the leaf or root, 6 GRAS genes in 3 differentially expressed gene clusters were involved in the salinity stress response in the leaf. Moreover, qRT-PCR results confirmed that MsGRAS51 expression was induced under drought stress and hormone treatments (ABA, GA and IAA) but down-regulated in salinity stress. Collectively, our genome-wide characterization, evolutionary, and expression analysis suggested that the MsGRAS proteins might play crucial roles in response to abiotic stresses and hormonal cues in alfalfa. For the breeding of alfalfa, it provided important information on stress resistance and functional studies on MsGRAS and hormone signaling.

Highlights

Transcription factors (TFs) as regulatory proteins could bind to specific DNA sequences, which might be located in the promoters of target genes, and play a vital role in plant development, as well as in response to abiotic stresses, such as drought, salt, chilling and heat [1]
We firstly retrieved 32 GRAS proteins (AtGRAS) in A. thaliana from the TAIR website
Search against the M. sativa genome of “Zhongmu No.1” [33], which was downloaded from the FIGSHARE database

Summary

Introduction

Transcription factors (TFs) as regulatory proteins could bind to specific DNA sequences (cis-acting elements), which might be located in the promoters of target genes, and play a vital role in plant development, as well as in response to abiotic stresses, such as drought, salt, chilling and heat [1]. The GRAS transcription factors are proposed to be plant-specific regulation proteins, which are supported by their possession of certain structural features [2]. The GRAS family was defined, after GAI (gibberellic acid insensitive), RGA (repressor of GA1–3 mutant), and scarecrow (SCR) were identified as family members. GAI and RGA play a vital role in the gibberellin-dependent signal transduction process, and SCR is involved in regulating the radial tissue differentiation in roots [3,4,5]. The N-terminal is the functional component of the GRAS protein, as its IDRs (intrinsically disordered regions) could bind with different other proteins [7]

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