Overexpression of CaWRKY27, a subgroup IIe WRKY transcription factor of Capsicum annuum, positively regulates tobacco resistance to Ralstonia solanacearum infection

Authors

  • Fengfeng Dang,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
    2. College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Yuna Wang,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
    2. Department of Life Science, Luoyang Normal University, Luoyang, Henan, China
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  • Jianju She,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Yufen Lei,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Zhiqin Liu,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Thomas Eulgem,

    1. Center for Plant Cell Biology, Institute for Integrative Genome Biology, Department of Botany and Plant Sciences, University of California at Riverside, Riverside, CA, USA
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  • Yan Lai,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Jing Lin,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Lu Yu,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Dan Lei,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Deyi Guan,

    1. College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Xia Li,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Qian Yuan,

    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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  • Shuilin He

    Corresponding author
    1. National Education Minster Key Laboratory of Plant Genetic Improvement and Comprehensive Utilization, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
    2. College of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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Abstract

WRKY proteins are encoded by a large gene family and are linked to many biological processes across a range of plant species. The functions and underlying mechanisms of WRKY proteins have been investigated primarily in model plants such as Arabidopsis and rice. The roles of these transcription factors in non-model plants, including pepper and other Solanaceae, are poorly understood. Here, we characterize the expression and function of a subgroup IIe WRKY protein from pepper (Capsicum annuum), denoted as CaWRKY27. The protein localized to nuclei and activated the transcription of a reporter GUS gene construct driven by the 35S promoter that contained two copies of the W-box in its proximal upstream region. Inoculation of pepper cultivars with Ralstonia solanacearum induced the expression of CaWRKY27 transcript in 76a, a bacterial wilt-resistant pepper cultivar, whereas it downregulated the expression of CaWRKY27 transcript in Gui-1-3, a bacterial wilt-susceptible pepper cultivar. CaWRKY27 transcript levels were also increased by treatments with salicylic acid (SA), methyl jasmonate (MeJA) and ethephon (ETH). Transgenic tobacco plants overexpressing CaWRKY27 exhibited resistance to R. solanacearum infection compared to that of wild-type plants. This resistance was coupled with increased transcript levels in a number of marker genes, including hypersensitive response genes, and SA-, JA- and ET-associated genes. By contrast, virus-induced gene silencing (VIGS) of CaWRKY27 increased the susceptibility of pepper plants to R. solanacearum infection. These results suggest that CaWRKY27 acts as a positive regulator in tobacco resistance responses to R. solanacearum infection through modulation of SA-, JA- and ET-mediated signaling pathways.

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