A genome-wide analysis of parasitic fitness in the Dutch elm disease fungus Ophiostoma novo-ulmi

自20世纪初以来，连续两次荷兰榆病(DED)大流行已导致超过10亿只榆树死亡。高度侵袭性的真菌Ophiostoma novo-ulmi是目前DED大流行的罪魁祸首，并对北美分布最广泛的本土榆树--美洲榆树的种群产生了巨大影响。了解导致DED的宿主-病原体相互作用的遗传基础是开发涉及操纵病原体或其宿主的控制方法的基础。这项拟议研究的总体目标是识别、表征和操纵有助于新生稻瘟病菌整体寄生适合度的基因。更具体地说，我们的目标是参与致病的基因，以及控制DED真菌在宿主中发育时在两种生长形式(酵母和菌丝体)之间转换的基因。 这项拟议的研究利用了我们多年来在分析O.novo-ulmi时开发的专业知识和资源。这些措施包括：1)广泛收集世界各地DED真菌的田间分离株；2)恢复适合度发生变化的突变株；3)在受控环境条件下的接种程序，以识别毒力降低的突变株；4)监测DED真菌在不同实验条件下的基因表达方法；以及5)获得O.novo-ulmi的全基因组序列。我们将使用最新的基因组技术(包括下一代测序)来广泛地寻找使新生乳杆菌成为如此成功的病原体的基因。 这项拟议工作的意义在于，一旦鉴定和表征了影响新月桂寄生适合度的基因，就有可能提出和开发新的方法来中断病原菌的生活史，以保护北美剩余的榆树种群。

More than one billion elms have been killed by two successive pandemics of Dutch elm disease (DED) since the early 20th century. The highly aggressive fungus Ophiostoma novo-ulmi is responsible for the current DED pandemic and has had a dramatic impact on populations of Ulmus americana, the most widespread native elm species in North America. Understanding the genetic basis of the host-pathogen interaction leading to DED is basic to developing control methods involving manipulation of the pathogen or its host. The general objective of the proposed research is to identify, characterize and manipulate genes that contribute to overall parasitic fitness in O. novo-ulmi. More specifically, we are targeting genes involved in pathogenicity, as well as genes that control the transition between the two growth forms (yeast and mycelium) observed in the DED fungi when they develop in their host. The proposed research takes advantage of the expertise and resources we have developed over the years in the analysis of O. novo-ulmi. These include 1) maintenance of an extensive collection of field isolates of DED fungi from around the world; 2) recovery of O. novo-ulmi mutants with altered fitness; 3) inoculation procedures under controlled environmental conditions for identifying mutants with reduced virulence; 4) methods for monitoring gene expression in DED fungi under different experimental conditions; and 5) access to the full genome sequence of O. novo-ulmi. We will use the latest genomic techniques (including Next Generation Sequencing) in an extensive search for genes that contribute making O. novo-ulmi such a successful pathogen. The significance of the proposed work is that once genes that contribute to parasitic fitness of O. novo-ulmi are identified and characterized, it becomes possible to propose and develop new ways to interrupt the life cycle of the pathogen, in order to protect the remaining elm populations in North America.