Investigating control of Ustilago maydis teliospore formation, dormancy and germination

农作物生产是价值数十亿美元的农业和农业食品部门的主要组成部分，该部门雇用了200多万加拿大人。这种生产受到真菌疾病增加的威胁，这些疾病是由大量耐药孢子传播的。目前的研究主要集中在疾病的形成上，但并没有找到对抗真菌疾病的新方法。在这里，我提出了另一个重点，阻止孢子的产生和疾病的传播，作为一个领域，可以开发新的方法来对抗真菌。自从发现微生物致病以来，我们就知道了孢子的作用。农作物真菌病的明显迹象往往与孢子的产生有关。然而，我们对真菌如何影响植物以帮助它们发育和传播孢子的了解有限。我的实验室开发了一种技术，利用常见的玉米黑穗病真菌，黑穗病菌，来研究真菌植物疾病。我们决定：1；真菌如何利用激素来确定孢子形成的时间；2. 2 .不同的真菌如何操纵宿主产生孢子；休眠孢子是如何变得活跃的我们发现，美氏菌产生细胞分裂素（ck），一种植物激素，在疾病发展时改变植物。maydis也可以在感染期间检测到ck，这表明它可能会监测ck的水平，以便确定孢子产生的时间。我们将研究当ck存在时，真菌和植物开启和关闭哪些基因。然后我们将确定改变这些基因的表达如何影响孢子的发育。我们发现，maydis可以与一种密切相关的真菌孢子菌（Sporisorium reilium）杂交产生杂种。双亲都感染玉米，但美氏球菌在感染部位周围产生疾病症状和孢子，而弧菌进入玉米并全身生长，只在穗轴和穗轴上产生疾病症状和孢子。杂交种在培养中生长得类似于美国maydis，但在植物中它们不产生孢子。我们将确定在感染过程中，在杂交种中哪些梅迪斯致病基因是开启或关闭的，以及改变某些基因的表达是否有助于杂交种形成孢子。这将确定在孢子产生中起作用的基因，并揭示杂交如何导致新型病原体。在第三个项目中，我们将研究疾病传播的另一个方面，即孢子的萌发。一旦形成，这些抵抗结构就会休眠。我们已经开发了工具来帮助我们研究芽孢杆菌如何控制孢子萌发时的代谢活动。理解这种回到疾病产生状态的过程是受控制的，可能会让我们发现阻止疾病发生和预防疾病传播的新方法。通过这项研究获得的知识将有助于开发防止真菌疾病传播的新方法，以提高作物生产的可持续性

Crop production is a major component of the multi-billion dollar agricultural and agrifood sector that employs over two million Canadians. This production is threatened by an increase in fungal diseases that are spread by massive numbers of resistant spores. The current research focus on disease formation has not produced new ways to fight fungal diseases. Here I present an alternative focus, blocking spore production and disease spread, as an area where novel approaches for battling fungi could be developed. We have known about the role of spores since the discovery that microbes cause disease. Obvious signs of fungal disease in crops are often associated with spore production. However our knowledge of how fungi influence plants to help them develop and disperse spores is limited. My laboratory has developed techniques for investigating fungal plant disease using the common corn smut fungus, Ustilago maydis. We are determining: 1. How the fungus uses hormones to time spore formation; 2. How different fungi manipulate the host to produce spores, and 3. How dormant spores become active We discovered that U. maydis produces cytokinins (CKs), plant hormones that alter the plant as disease develops. U. maydis can also detect CKs during infection suggesting that it might monitor levels of CKs in order to time the production of its spores. We will investigate which genes the fungus and the plant turn on and off when CKs are present. Then we will determine how altering the expression of these genes influences spore development. We found that U. maydis can cross with a closely related fungus Sporisorium reilianum to produce hybrids. Both parents infect maize but U. maydis produces disease symptoms and spores around the site of infection, whereas, S. reilianum enters maize and grows systemically producing disease symptoms and spores only in the tassels and cobs. The hybrids grow similar to U. maydis in culture but in the plant they do not produce spores. We will determine which of the U. maydis pathogenesis genes are turned on or off in the hybrid during infection and whether changing the expression of certain genes can help the hybrid form spores. This will identify genes with roles in spore production and uncover how hybridization could lead to new types of pathogens. In the third project we will investigate another aspect of disease spread, the germination of spores. When formed, these resistant structures become dormant. We have developed tools to help us study how U. maydis controls the return to metabolic activity as spores germinate. Understanding this return to a disease producing state is controlled may allow us to uncover novel ways of stopping it and of preventing disease spread. The knowledge gained through this research will contribute to the development of novel approaches for preventing fungal disease spread to improve the sustainability of crop production