PLOS Pathogens:中科院微生物所郭惠珊研究组发表棉花黄萎菌研究进

2016年7月14日，国际微生物学知名期刊《PLOS Pathogens》在线发表了中国科学院微生物研究所植物基因组学国家重点实验室郭惠珊研究员的一篇研究论文，论文报道了棉花黄萎菌附着枝的分子特征及其在致病作用中所扮演的角色。

棉花黄萎病菌是专性根感染的一种植物致病真菌。在根表面的分生孢子萌发后(用以进一步感染)，一些附着枝(hyphopodia)与大量菌丝有所不同。然而，附着枝的分子特征及其在黄萎病菌的致病作用中扮演了什么角色，尚不清楚。

在这项研究中，研究人员发现，VdPls1——一个跨膜四蛋白，和VdNoxB——膜结合NADPH氧化酶的一个催化亚基，用于活性氧(ROS)的生产，在附着枝中特异性地表达。VdPls1和VdNoxB与附着枝基部的质膜高度共定位，在那里产生了ROS和侵入钉。突变株——VdΔnoxb和VdΔpls1，其中VdPls1和VdNoxB被删除，分别发展出了有缺陷的附着枝，不能产生ROS和侵入钉。在VdΔpls1中，VdNoxB的缺陷性质膜定位表明，VdPls1的功能是一个接头蛋白，以招募和激活VdNoxB。

此外，在VdΔnoxb和VdΔpls1中，附着枝中——而不是营养菌丝顶端——的钙积累受损。此外，在野生型棉花黄萎菌中VdCrz1的细胞核定位和附着枝诱导的钙调磷酸酶-Crz1信号激活，在两种基因敲除突变体中都受损，表明VdPls1/VdNoxB依赖的ROS，对于附着枝中Ca2+升高以激活调控侵入钉形成的调控转录因子VdCrz1来说，是必需的。

连同VdΔnoxb和VdΔpls1的毒力损失，这些数据表明，VdNoxB/VdPls1介导的ROS激活可通过附着枝(棉花黄萎病菌传染的结构)中的Ca2+升高而刺激VdCrz1信号，在棉花根系的初始定植阶段调节侵入钉的形成。

原文链接：

Hyphopodium-Specific VdNoxB/VdPls1-Dependent ROS-Ca2+Signaling Is Required for plant Infection by Verticillium dahliae

原文摘要：

Verticillium dahliae is a phytopathogenic fungus obligate in root infection. A few hyphopodia differentiate from large numbers of hyphae after conidia germination on the root surface for further infection. However, the molecular features and role of hyphopodia in the pathogenicity ofV. dahliae remain elusive. In this study, we 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. Mutant strains, VdΔnoxb and VdΔpls1, in which VdPls1 and VdNoxB were deleted, respectively, developed defective hyphpodia incapable of producing ROS and penetration pegs. Defective plasma membrane localization of VdNoxB in VdΔpls1demonstrates that VdPls1 functions as an adaptor protein for the recruitment and activation of the VdNoxB. Furthermore, in VdΔnoxb and VdΔpls1, tip-high Ca2+ accumulation was impaired in hyphopodia, but not in vegetative hyphal tips. Moreover, nuclear targeting of VdCrz1 and activation of calcineurin-Crz1 signaling upon hyphopodium induction in wild-type V. dahliae was impaired in both knockout mutants, indicating that VdPls1/VdNoxB-dependent ROS was specifically required for tip-high Ca2+ elevation in hyphopodia to activate the transcription factorVdCrz1 in the regulation of penetration peg formation. Together with the loss of virulence of VdΔnoxb and VdΔpls1, which are unable to initiate colonization in cotton plants, our data demonstrate that VdNoxB/VdPls1-mediated ROS production activates VdCrz1 signaling through Ca2+ elevation in hyphopodia, infectious structures of V. dahliae, to regulate penetration peg formation during the initial colonization of cotton roots.

doi:10.1371/journal.ppat.1005793

作者：郭惠珊