Scientists reveal mechanism of infection process of Verticillium dahliae

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Updatetime:2016-08-26
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Verticillium dahliae Kleb. is a soil-borne fungal pathogen that causes wilt disease in a wide range of crops, including cotton, and causes serious loss of lint in China. Infection of cotton roots by V. dahliae in soil leads to the colonization of vascular tissues in host plants. However, the development of specialized infection structures to overcome plant barriers during root infection by V. dahliae has been controversial. Moreover, the molecular features and regulation mechanism in infection process ofV. dahliae remain elusive.

Dr. Guo Huishan’s group in the State Key Laboratory of Plant Genomics, Institute of Microbiology of Chinese Academy of Sciences, provides for the first time the molecular features for accurate identification of hyphopodium, an infectious structure in V. dahliae. They found that the VdPls1, a tetraspanin, and the VdNoxB, a catalytic subunit of membrane-bound NADPH oxidases for reactive oxygen species (ROS) production, were specifically expressed in hyphopodia. VdPls1 and VdNoxB highly co-localize with the plasma membrane at the base of hyphopodia, where ROS and penetration pegs are generated. The strain with deletion of VdPls1 or VdNoxB  developed defective hyphpodia incapable of producing ROS and penetration pegs. Moreover, they found that VdPls1/VdNoxB-mediated ROS production elevates tip-high cytoplasmic free calcium ions (Ca2+) in hyphopodia to activate conservation calcineurin-Crz1 signaling for the establishment polarized penetration peg formation. Together with the loss of virulence when VdPls1 or VdNoxB was deleted, their data demonstrate that VdNoxB/VdPls1-mediated ROS production activates VdCrz1 signaling through Ca2+ elevation in hyphopodia, infectious structures of Vdahliae, to regulate penetration peg formation during the initial colonization of cotton roots.

      The paper entitled “Hyphopodium-Specific VdNoxB/VdPls1-Dependent ROS-Ca2+ Signaling Is Required for Plant Infection by Verticillium dahliae” has been published online in PLoS Pathogens with the Ph.D. student Zhao Yunlong as the first author and Dr. Guo as corresponding author. This work was supported by grants from the Strategic Priority Research Program of the Chinese Academy of Sciences and the China Transgenic Research and Commercialization Key Special Project.

Figure: Hyphopodium-specific VdNoxB/VdPls1-dependent ROS-Ca2+ signaling regulates penetration peg development and plant infection by V. dahliae.

A. Hyphopodium (HP) differentiation in wild-type V. dahliae strain V592; B. HP-specific Ca2+ elevation in V592; C. ROS generation and penetration peg development, as well as colonization of vascular tissues in cotton root by V592 but not VdNoxB deletion mutant; D. Schematic overview of VdNoxB/VdPls1-depedent ROS-Ca2+ signaling for penetration formation in V. dahliae.

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