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CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40
WRKY transcription factors (TFs) have been implicated in plant growth, development, and in response to environmental cues; however, the function of the majority of pepper WRKY TFs remains unclear. In the present study, we functionally characterized CaWRKY40b, a homolog of AtWRKY40, in pepper immunit...
Autores principales: | , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983674/ https://www.ncbi.nlm.nih.gov/pubmed/29738468 http://dx.doi.org/10.3390/ijms19051403 |
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author | Ifnan Khan, Muhammad Zhang, Yangwen Liu, Zhiqin Hu, Jiong Liu, Cailing Yang, Sheng Hussain, Ansar Furqan Ashraf, Muhammad Noman, Ali Shen, Lei Xia, Xiaoqin Yang, Feng Guan, Deyi He, Shuilin |
author_facet | Ifnan Khan, Muhammad Zhang, Yangwen Liu, Zhiqin Hu, Jiong Liu, Cailing Yang, Sheng Hussain, Ansar Furqan Ashraf, Muhammad Noman, Ali Shen, Lei Xia, Xiaoqin Yang, Feng Guan, Deyi He, Shuilin |
author_sort | Ifnan Khan, Muhammad |
collection | PubMed |
description | WRKY transcription factors (TFs) have been implicated in plant growth, development, and in response to environmental cues; however, the function of the majority of pepper WRKY TFs remains unclear. In the present study, we functionally characterized CaWRKY40b, a homolog of AtWRKY40, in pepper immunity. Ralstonia solanacearum inoculation (RSI) in pepper plants resulted in downregulation of CaWRKY40b transcript, and green fluorescent protein (GFP)-tagged CaWRKY40b was localized to the nuclei when transiently overexpressed in the leaves of Nicotiana benthamiana. Virus-induced gene silencing (VIGS) of CaWRKY40b significantly decreased pepper’ susceptibility to RSI. Consistently, the transient over-expression of CaWRKY40b-SRDX (chimeric repressor version of CaWRKY40b) triggered cell death, as indicated by darker trypan blue and DAB staining. CaWRKY40b targets a number of immunity-associated genes, including CaWRKY40 JAR, RLK1, EIN3, FLS2, CNGIC8, CDPK13, and heat shock cognate protein 70 (HSC70), which were identified by ChIP-seq and confirmed using ChIP-real time PCR. Among these target genes, the negative regulator HSC70 was upregulated by transient overexpression of CaWRKY40b and downregulated by silencing of CaWRKY40b, whereas other positive regulators as well as two non-target genes, CaNPR1 and CaDEF1, were downregulated by the transient overexpression of CaWRKY40b and upregulated by CaWRKY40b silencing or transient overexpression of CaWRKY40b-SRDX. In addition, CaWRKY40b exhibited a positive feedback regulation at transcriptional level by directly targeting the promoter of itself. In conclusion, the findings of the present study suggest that CaWRKY40b acts as a negative regulator in pepper immunity against R. solanacearum by transcriptional modulation of a subset of immunity-associated genes; it also represses immunity in the absence of a pathogen, and derepresses immunity upon pathogen challenge. |
format | Online Article Text |
id | pubmed-5983674 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-59836742018-06-05 CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40 Ifnan Khan, Muhammad Zhang, Yangwen Liu, Zhiqin Hu, Jiong Liu, Cailing Yang, Sheng Hussain, Ansar Furqan Ashraf, Muhammad Noman, Ali Shen, Lei Xia, Xiaoqin Yang, Feng Guan, Deyi He, Shuilin Int J Mol Sci Article WRKY transcription factors (TFs) have been implicated in plant growth, development, and in response to environmental cues; however, the function of the majority of pepper WRKY TFs remains unclear. In the present study, we functionally characterized CaWRKY40b, a homolog of AtWRKY40, in pepper immunity. Ralstonia solanacearum inoculation (RSI) in pepper plants resulted in downregulation of CaWRKY40b transcript, and green fluorescent protein (GFP)-tagged CaWRKY40b was localized to the nuclei when transiently overexpressed in the leaves of Nicotiana benthamiana. Virus-induced gene silencing (VIGS) of CaWRKY40b significantly decreased pepper’ susceptibility to RSI. Consistently, the transient over-expression of CaWRKY40b-SRDX (chimeric repressor version of CaWRKY40b) triggered cell death, as indicated by darker trypan blue and DAB staining. CaWRKY40b targets a number of immunity-associated genes, including CaWRKY40 JAR, RLK1, EIN3, FLS2, CNGIC8, CDPK13, and heat shock cognate protein 70 (HSC70), which were identified by ChIP-seq and confirmed using ChIP-real time PCR. Among these target genes, the negative regulator HSC70 was upregulated by transient overexpression of CaWRKY40b and downregulated by silencing of CaWRKY40b, whereas other positive regulators as well as two non-target genes, CaNPR1 and CaDEF1, were downregulated by the transient overexpression of CaWRKY40b and upregulated by CaWRKY40b silencing or transient overexpression of CaWRKY40b-SRDX. In addition, CaWRKY40b exhibited a positive feedback regulation at transcriptional level by directly targeting the promoter of itself. In conclusion, the findings of the present study suggest that CaWRKY40b acts as a negative regulator in pepper immunity against R. solanacearum by transcriptional modulation of a subset of immunity-associated genes; it also represses immunity in the absence of a pathogen, and derepresses immunity upon pathogen challenge. MDPI 2018-05-08 /pmc/articles/PMC5983674/ /pubmed/29738468 http://dx.doi.org/10.3390/ijms19051403 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Ifnan Khan, Muhammad Zhang, Yangwen Liu, Zhiqin Hu, Jiong Liu, Cailing Yang, Sheng Hussain, Ansar Furqan Ashraf, Muhammad Noman, Ali Shen, Lei Xia, Xiaoqin Yang, Feng Guan, Deyi He, Shuilin CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40 |
title | CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40 |
title_full | CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40 |
title_fullStr | CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40 |
title_full_unstemmed | CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40 |
title_short | CaWRKY40b in Pepper Acts as a Negative Regulator in Response to Ralstonia solanacearum by Directly Modulating Defense Genes Including CaWRKY40 |
title_sort | cawrky40b in pepper acts as a negative regulator in response to ralstonia solanacearum by directly modulating defense genes including cawrky40 |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983674/ https://www.ncbi.nlm.nih.gov/pubmed/29738468 http://dx.doi.org/10.3390/ijms19051403 |
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