Molecular genetics of smut fungi

我们的长期目标是了解真菌病原体如何引起对加拿大经济重要的作物和树木的疾病。最终，我们希望为植物保护和可持续农业的新战略做出贡献。我们研究了与加拿大相关的谷物作物的病原体，包括玉米病原体黑穗病菌。这种真菌会引起一种严重的疾病，使玉米穗变成巨大的肿瘤，最终充满黑色的真菌孢子团块（因其黑色、煤烟状的外观而被称为黑穗病）。这些孢子传播疾病并污染未感染植物的谷物。麦氏真菌对玉米生产是一种威胁，也是一种有价值的实验生物，用于了解其他相关真菌病原体如何导致小麦、大麦和燕麦的作物产量和质量的重大损失。***在我们的项目中，我们专门研究了U. maydis入侵植物所需的特化细胞（丝）的形成和增殖。我们还想了解病原体如何感知植物宿主的环境，以及它在入侵后如何获取营养。我们的工作导致发现内源性真菌因子（交配信号），脂质和磷酸盐作为信号和营养物质，影响丝状真菌在感染期间的生长。最近，我们利用最先进的分子技术鉴定了美国玉米约6500个基因和约32000个玉米基因在疾病期间的表达变化。这项工作揭示了真菌获取养分的关键特征和植物中重要的防御变化。重要的是，我们发现病原体的感染会导致代谢（例如光合作用）和防御所需的关键植物结构（叶绿体）的破坏。***为了利用我们的发现，我们计划使用最新的蛋白质测量技术来确定哪些预测的病原体蛋白质（6500种）实际上进入叶绿体造成损害并阻碍植物防御。我们进行了初步实验，以确认我们可以识别这些蛋白质，现在我们有了初步的候选名单。同时，我们计划使用分析方法测量与叶绿体功能和防御相关的化学物质的变化。总之，这些实验将提供一幅关于美国黄蜂如何攻击玉米植物的详细图片。随后，我们将使用遗传技术来阻止特定的U. maydis蛋白质破坏叶绿体的能力，我们将使用生化技术来确定关键蛋白质的作用机制。鉴定这些蛋白质很重要，因为它们的特性可能揭示控制真菌疾病和保护作物的新策略。

Our long-term goal is to understand how fungal pathogens cause diseases on crops and trees of economic importance to Canada. Ultimately, we want to contribute to new strategies for plant protection and sustainable agriculture. We study pathogens that attack cereal crops of relevance to Canada including the corn pathogen Ustilago maydis. This fungus causes a dramatic disease in which ears of corn are converted to large tumors that eventually fill with black masses of fungal spores (called smuts because their black, sooty appearance). These spores spread the disease and contaminate grain from uninfected plants. U. maydis is a threat to corn production and it is also a valuable experimental organism for understanding other how related fungal pathogens cause substantial losses in crop yield and quality for wheat, barley and oats. *** In our program, we specifically investigate the formation and proliferation of specialized cells (filaments) of U. maydis that are required to invade plants. We also want to understand how the pathogen senses the environment of the plant host and how it obtains nutrients after invasion. Our work led to the discovery of endogenous fungal factors (mating signals), lipids and phosphate as signals and nutrients that influence filamentous growth during infection. Recently, we employed state of the art molecular technology to identify changes in expression during disease for all of the approximately 6,500 genes of U. maydis and all of the approximately 32,000 corn genes. This work revealed key features of nutrient acquisition by the fungus and important defense changes in the plant. Importantly, we discovered that infection by the pathogen results in destruction of the key plant structures (chloroplasts) required for metabolism (photosynthesis for example) and defense. *** To take advantage of our discoveries, we plan to use the latest technologies for measuring proteins to determine which of the predicted pathogen proteins (out of 6,500) actually enter chloroplasts to cause damage and block plant defense. We performed a preliminary experiment to confirm that we can identify these proteins and we now have a preliminary list of candidates. In parallel, we plan to measure changes in chemicals associated with chloroplast function and defense using analytical methods. Together, these experiments will provide a detailed picture of how U. maydis attacks corn plants. Subsequently, we will use genetic techniques to block the ability of specific U. maydis proteins to damage chloroplasts, and we will use biochemical techniques to determine the mechanism(s) of action of key proteins. It is important to identify these proteins because their characterization may reveal new strategies to control fungal diseases and protect crops.