Abstract
The WRKY gene family has never been identified in pigeonpea (Cajanus cajan). Therefore, objective of the present study was to identify the WRKY gene family in pigeonpea and characterize the Fusarium udum stress-responsive WRKY genes under normal, NaCl-stressed and Pseudomonas fluorescens OKC (a plant growth-promoting bacterial strain) treated conditions. The aim was to characterize the Fusarium udum stress-responsive WRKY genes under some commonly occurring field conditions. We identified 97 genes in the WRKY family of pigeonpea, using computational prediction method. The gene family was then classified into three groups through phylogenetic analysis of the homologous genes from the representative plant species. Among the 97 identified WRKY genes 35 were further classified as pathogen stress responsive genes. Functional validation of the 35 WRKY genes was done through generating transcriptional profiles of the genes from root tissues of pigeonpea plants under the influence of P. fluorescens OKC after 24 h of stress application (biotic: Fusarium udum, abiotic: NaCl). The entire experiment was conducted in two pigeonpea cultivars Asha (resistant to F. udum) and Bahar (susceptible to F. udum) and the results were concluded on the basis of transcriptional regulation of the WRKY genes in both the pigeonpea cultivars. The results revealed that among the 35 tentatively identified biotic stress responsive CcWRKY genes, 26 were highly F. udum responsive, 17 were better NaCl responsive compared to F. udum and 11 were dual responsive to both F. udum and NaCl. Application of OKC was able to enhance transcript accumulation of the individual CcWRKY genes to both the stresses when applied individually but not in combined challenge of the two stresses. The results thus indicated that CcWRKY genes play a vital role in the defense signaling against F. udum and some of the F. udum responsive CcWRKYs (at least 11 in pigeonpea) are also responsive to abiotic stresses such as NaCl. Further, plant beneficial microbes such as P. fluorescens OKC also help pegionpea to defend itself against the two stresses (F. udum and NaCl) through enhanced expression of the stress responsive CcWRKY genes when the stresses are applied individually.
Highlights
The WRKY family of transcription factors (TFs) is one of the most important gene families in higher plants involved in biotic and abiotic stress responses[1]
The aim of the present study is to (i) identify and validate the tentative WRKY TFs of pigeonpea that respond to F. udum challenge, (ii) considering the increasing areas of salinity in cultivable lands, the same set of WRKY genes was evaluated for their responsiveness to NaCl stress either individually or in combination with F. udum and (iii) a plant growth-promoting rhizobacteria (PGPR) Pseudomonas fluorescens OKC, a potential plant stress reliever, was used to see its impact on the selected WRKY genes under both F. udum and NaCl stresses in pigeonpea
Phylogenetic relationship study showed that the CcWRKY proteins in pigeonpea could be categorized into three groups, Group I–III, which are highly conserved in both monocots and eudicots[8] (Fig. 1)
Summary
The WRKY family of transcription factors (TFs) is one of the most important gene families in higher plants involved in biotic and abiotic stress responses[1]. WRKY family proteins have been classified into three groups (I-III) based on the WRKY domain numbers as well as structure of the zinc-finger motif. Group II WRKY proteins possess a single WRKY domain along with a C2H2 like zinc-finger motif. Group III WRKY proteins possess a single WRKY domain in addition to a C2HC type zinc-finger motif. The aim of the present study is to (i) identify and validate the tentative WRKY TFs of pigeonpea that respond to F. udum challenge, (ii) considering the increasing areas of salinity in cultivable lands, the same set of WRKY genes was evaluated for their responsiveness to NaCl stress either individually or in combination with F. udum and (iii) a plant growth-promoting rhizobacteria (PGPR) Pseudomonas fluorescens OKC, a potential plant stress reliever, was used to see its impact on the selected WRKY genes under both F. udum and NaCl stresses in pigeonpea
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
