GmWRKY49, a Salt-Responsive Nuclear Protein, Improved Root Length and Governed Better Salinity Tolerance in Transgenic Arabidopsis.

Zhaolong Xu,Hongxiang Ma,Ling Xu,Qasim Raza,Dayong Zhang,Zulfiqar Ali,Yihong Huang,Jinxin Yi,Xiaolan He,Hong-Bo Shao

doi:10.3389/fpls.2018.00809

Abstract

Plant WRKY transcription factors (TFs) are active guardians against pathogens’ insurgency, key components in developmental processes, contributors in signal transduction pathways, and regulators of diverse biotic and abiotic stress responses. In this research, we isolated, cloned, and functionally characterized a new WRKY TF GmWRKY49 from soybean. GmWRKY49 is a nuclear protein which contains two highly conserved WRKY domains and a C2H2-type zinc-finger structure. The normalized expression (log2 ratio) of GmWRKY49 was 2.75- and 1.90-fold in salt-tolerant and salt-susceptible soybean genotypes, respectively. The transcripts of GmWRKY49 could be detected in roots, stems, leaves, flowers, and almost no expression in pod tissues. The salinity-tolerance response of this gene was studied through overexpression in soybean composite seedlings and transgenic Arabidopsis. The effect of GmWRKY49 overexpression on root length of transgenic Arabidopsis was also investigated. Under salt stress, several parameters including germination rate, survival rate, root length, rosette diameter, relative electrolyte leakage, and proline content were significantly higher in composite seedlings and transgenic Arabidopsis than those in wild-type. Moreover, GmWRKY49 enhanced salinity tolerance in soybean mosaic seedlings and transgenic Arabidopsis. These results suggest that GmWRKY49 is a positive regulator of salinity tolerance in soybean and has high potential utilization for crop improvement.

Highlights

Being sessile, plants are forced to cope with their immediate environment and encounter multiple biotic and abiotic stresses simultaneously
The second group was further categorized into five subgroups, named IIa, IIb, IIc, IId, and IIe (Figure 1A)
GmWRKY49 contains two WRKY domains, a C2H2-type Zn-finger motif and is most similar to AtWRKY33 and both belong to group I (Figure 1A)

Summary

Introduction

Plants are forced to cope with their immediate environment and encounter multiple biotic and abiotic stresses simultaneously. Several stress-responsive TF families such as WRKY, bZIPs, AP2/ERF, DREB, MYB, and NAC are reported to be involved in biotic and abiotic stress responses (Chen et al, 2007; Liao et al, 2008; Nuruzzaman et al, 2013; Llorca et al, 2014; Phukan et al, 2016; Gu et al, 2017). These TFs bind to specific cis-acting elements in the promoter region (Dolfini et al, 2012) and modulate the expression of several stress-responsive genes. Some TFs have been recently engineered to enhance salt-tolerance (Xu et al, 2016; Hichri et al, 2017; Li et al, 2017)

Methods

Results

Discussion

Conclusion