Virus-induced gene silencing reveals the involvement of ethylene-, salicylic acid- and mitogen-activated protein kinase-related defense pathways in the resistance of tomato to bacterial wilt

Authors

  • Yong-Yi Chen,

    1. Graduate Institute of Plant Biology and Department of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan 106, Republic of China
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    • These authors contributed equally to this work.

  • Yu-Mei Lin,

    1. Graduate Institute of Plant Biology and Department of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan 106, Republic of China
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    • These authors contributed equally to this work.

  • To-Chun Chao,

    1. Graduate Institute of Plant Biology and Department of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan 106, Republic of China
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  • Jaw-Fen Wang,

    1. AVRDC—The World Vegetable Center, PO Box 42, Shanhua, Tainan, Taiwan 741, Republic of China
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  • An-Chi Liu,

    1. Graduate Institute of Plant Biology and Department of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan 106, Republic of China
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  • Fang-I Ho,

    1. AVRDC—The World Vegetable Center, PO Box 42, Shanhua, Tainan, Taiwan 741, Republic of China
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  • Chiu-Ping Cheng

    Corresponding author
    1. Graduate Institute of Plant Biology and Department of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan 106, Republic of China
      *e-mail: chiupingcheng@ntu.edu.tw
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*e-mail: chiupingcheng@ntu.edu.tw

Abstract

Bacterial wilt (BW), caused by Ralstonia solanacearum, is a devastating vascular disease of tomato worldwide. However, information on tomato's defense mechanism against infection by this soil-borne bacterium is limited. In this study, virus-induced gene silencing (VIGS) was employed to decipher signaling pathways involved in the resistance of tomato to this pathogen. Defined sequence fragments derived from a group of genes known or predicted to be involved in ethylene (ET) and salicylic acid (SA) signaling transduction pathways and mitogen-activated protein kinase (MAPK) cascades were subjected to VIGS in ‘Hawaii 7996′, a tomato cultivar with stable resistance to BW, and their effect on resistance was determined. The results indicated that silencing of ACO1/3, EIN2, ERF3, NPR1, TGA2.2, TGA1a, MKK2, MPK1/2 and MPK3 caused significant increase in bacterial proliferation in stembases and/or mid-stems. Partial wilting symptoms appeared on plants in which TGA2.2, TGA2.1a, MKK2 and MPK1/2 were silenced. These results suggested that ET-, SA- and MAPK-related defense signaling pathways are involved in the resistance of tomato to BW. This is the first report elucidating the multiple layers of defense governing the resistance of tomato to BW. The results are discussed to enlighten an important and complex interaction between tomato and a soil-borne vascular pathogen.

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