Characterization of the molecular pathways that direct development and pathogenicity in the vascular wilt fungus Verticillium dahliae

大丽轮枝菌（Verticillium dahliae）是一种丝状真菌，其引起广泛的经济上重要的一年生和多年生作物的维管枯萎。 在感染过程中，真菌被限制在植物的导水（维管）系统中，以菌丝和酵母样细胞的两种形态生长（两种形式）。 在疾病的晚期阶段，大丽轮枝菌从维管系统逃逸到周围组织中，在那里产生其存活结构。 这些哈代的、着色的细胞簇与植物碎片一起分散到土壤中，可以在土壤中存活至少十年，并且是疾病接种物的主要来源。 参与这些结构的发展的分子途径，以及在植物中的二态生长为疾病控制提供了有吸引力的潜在目标。 在我实验室以前的研究中，我们发现疏水蛋白（疏水蛋白VDH 1）和自噬过程（细胞的细胞内循环系统）对于生存结构的发育至关重要。 另一个重要的发现是，VDH 1在感染的早期阶段被植物识别，以诱导植物防御反应，但植物无法维持这些防御。 分子策略将用于解决拟议研究中的两个主要目标。 第一个将是更好地定义生存结构发育途径，并确定该途径中可能被阻断以防止植物的生存结构形成和/或病原体定殖的步骤。 第二个目标是确定尚未表征的大丽轮枝菌疏水蛋白在存活结构发育和植物识别诱导植物防御中的作用。 将启动研究，以确定病原体使用何种分子机制来阻碍由病原体识别引发的植物防御反应。 拟议的研究结果将提供知识，为未来发展的新的，急需的疾病控制策略，以管理黄萎病。 由此产生的数据也预计是相关的其他病原真菌的研究，植物维管系统是首选的环境生态位。

Verticillium dahliae is a filamentous fungus that causes vascular wilt of a broad range of economically important annual and perennial crops. During infection the fungus is confined to the plant's water-conducting (vascular) system, growing dimorphically (in two forms), as hyphal and yeast-like cells. In the late stages of disease V. dahliae escapes from the vascular system into the surrounding tissues where it produces its survival structures. These hardy, pigmented clusters of cells are dispersed into the soil with plant debris, can survive for at least a decade in the soil, and are the primary source of disease inoculum. The molecular pathways involved in development of these structures, and in planta dimorphic growth offer attractive potential targets for disease control. In previous studies in my lab we showed that both a hydrophobic protein (hydrophobin VDH1) and the process of autophagy (the cells' intracellular recycling system) are essential for survival structure development. The other important discovery was that VDH1 is recognized by the plant during the early phase of infection to induce plant defence responses, but that the plant is unable to sustain those defences. Molecular strategies will be used to address two major objectives in of the proposed research. The first will be to better define the survival structure developmental pathway, and to identify steps in the pathway that could potentially be blocked to prevent survival structure formation and/or pathogen colonization of the plant. The second objective will be to determine the roles of as-yet uncharacterized V. dahliae hydrophobins during survival structure development and in plant recognition to induce plant defences. Studies will be initiated to determine what molecular mechanism(s) the pathogen uses to thwart the plant defence responses that are triggered by recognition of the pathogen. The results of the proposed research would provide knowledge for future development of new, and badly needed disease control strategies to manage verticillium wilt. The resulting data are also anticipated to be relevant to studies of other pathogenic fungi for which the plant vascular system is the preferred environmental niche.