Genome-Wide Analysis of MADS-Box Genes in Foxtail Millet (Setaria italica L.) and Functional Assessment of the Role of SiMADS51 in the Drought Stress Response.

Wan Zhao,Li-Li Zhang,Liang Fu,You-Zhi Ma,Hong-Xi Pang,Dong-Hong Min,Zhao-Shi Xu

doi:10.3389/fpls.2021.659474

Abstract

MADS-box transcription factors play vital roles in multiple biological processes in plants. At present, a comprehensive investigation into the genome-wide identification and classification of MADS-box genes in foxtail millet (Setaria italica L.) has not been reported. In this study, we identified 72 MADS-box genes in the foxtail millet genome and give an overview of the phylogeny, chromosomal location, gene structures, and potential functions of the proteins encoded by these genes. We also found that the expression of 10 MIKC-type MADS-box genes was induced by abiotic stresses (PEG-6000 and NaCl) and exogenous hormones (ABA and GA), which suggests that these genes may play important regulatory roles in response to different stresses. Further studies showed that transgenic Arabidopsis and rice (Oryza sativa L.) plants overexpressing SiMADS51 had reduced drought stress tolerance as revealed by lower survival rates and poorer growth performance under drought stress conditions, which demonstrated that SiMADS51 is a negative regulator of drought stress tolerance in plants. Moreover, expression of some stress-related genes were down-regulated in the SiMADS51-overexpressing plants. The results of our study provide an overall picture of the MADS-box gene family in foxtail millet and establish a foundation for further research on the mechanisms of action of MADS-box proteins with respect to abiotic stresses.

Highlights

Transcription factors play multiple roles over the entire life cycle of higher plants (Riechmann and Ratcliffe, 2000; Singh et al, 2002)
A total of 72 candidate genes encoding MADS-box domain (SRF-transcription factor (TF)) were identified in the foxtail millet (Setaria italica L.) genome and named as SiMADS01∼SiMADS72 based on their chromosomal locations
To investigate the phylogenetic relationships among MADS-box proteins in monocotyledons and dicotyledons, a phylogenetic tree was constructed with 488 MADS-box protein sequences from Arabidopsis (109), potato (Solanum tuberosum) (156), rice (Oryza sativa L.) (75), foxtail millet (72), and Setaria viridis (76)

Summary

Introduction

Transcription factors play multiple roles over the entire life cycle of higher plants (Riechmann and Ratcliffe, 2000; Singh et al, 2002). According to the PlantTFDB4.01, 320,370 TFs from 165 plant species have been classified into 58 families (Jin et al, 2018) Among these families, MADS-box proteins comprise a large TF family and are ubiquitous in the plant kingdom (Alvarez-Buylla et al, 2008; Zhang et al, 2018). Based on the evolutionary relationships and sequence characterization, Alvarez-Buylla et al (2008) classified MADS-box proteins into two major types, Type I and Type II, and they all have one thing in common; both types contain a MADS-box domain. Type I MADS-box genes in plants contain one or two exons, none or one intron, and the proteins encoded usually contain a highly conserved SRF-like MADS domain but lack a K domain (De Bodt et al, 2003b; Gramzow and Theißen, 2010). MADS-box genes mostly share similar expression patterns and the proteins perform highly related functions

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