Characterization and co-expression analysis of WRKY orthologs involved in responses to multiple abiotic stresses in Pak-choi (Brassica campestris ssp. chinensis)

Jun Tang,Aisheng Xiong,Xilin Hou,Feng Wang,Zhen Wang,Zhinan Huang

doi:10.1186/1471-2229-13-188

Abstract

BackgroundThe WRKY transcription factor is an important member of the stress-related transcription factors, which mediate diverse abiotic stresses in many plants. However, up until now, the number of WRKY members, and the regulatory mechanisms involved in abiotic stress responses in Pak-choi (Brassica campestris ssp. chinensis), remained unknown.ResultsWe isolated and identified 56 full-length WRKY cDNAs from a Pak-choi stress-induced cDNA library. The 56 putative BcWRKY proteins were divided into three groups based on structural and phylogenetic analyses. A subcellular localization prediction indicated that the putative BcWRKY proteins were enriched in the nuclear region. Experiments involving BcWRKY25 and BcWRKY40 confirmed the prediction. A total of 22 BcWRKYs were differentially expressed in response to at least one stress condition (abscisic acid, cold, salinity, heat, or osmosis) tested on Pak-choi leaves, and a co-expression analysis indicated stress-inducible BcWRKYs co-regulated multiple abiotic stresses. BcWRKY33, BcWRKY40, BcWRKY53, and BcWRKY70 acted as key regulators and played dominant roles within co-regulatory networks of stress-inducible BcWRKYs.ConclusionsWe first isolated and characterized the 56 stress-inducible WRKY transcription factor family members. A total of 22 stress-inducible BcWRKYs found in leaves can co-regulate multiple environmental stresses by integrating the potential mutual interactions of WRKYs in Pak-choi. This information will be valuable when exploring the molecular mechanisms of WRKYs in response to abiotic stresses in plants.

Highlights

The WRKY transcription factor is an important member of the stress-related transcription factors, which mediate diverse abiotic stresses in many plants
AtWRKY63 is involved in plant responses to abscisic acid (ABA) and drought tolerance [22], and At WRKY34 mediates the cold sensitivity of mature pollen in Arabidopsis [23]
Cloning stress-inducible BcWRKY genes from Pak-choi We isolated 56 BcWRKY genes from a multiple abiotic stress-treated Pak-choi cDNA library using a homology cloning method, which was based on sequence information from the A. thaliana WRKY gene family and the Chinese cabbage chiifu genome

Summary

Introduction

The WRKY transcription factor is an important member of the stress-related transcription factors, which mediate diverse abiotic stresses in many plants. Up until now, the number of WRKY members, and the regulatory mechanisms involved in abiotic stress responses in Pak-choi The WRKY TFs are important members of the stress-related TFs involved in regulating the plant’s environmental stress responses [4,5,6]. WRKY TFs have been found to be responsive to various abiotic stresses, including salinity, drought, cold, heat, and abscisic acid (ABA) signaling [16,17,18,19,20]. AtWRKY63 is involved in plant responses to ABA and drought tolerance [22], and At WRKY34 mediates the cold sensitivity of mature pollen in Arabidopsis [23]. BcWRKY46, a novel cold-inducible gene from Pak-choi (B. campestris ssp. chinensis, synonym of B. rapa ssp. chinensis) enhances the cold, salt and dehydration stress tolerance in transgenic tobacco [26]

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