Collaborative Research: Sudden Oak Death: Feedback Between a Generalist Pathogen, Hosts, and Heterogeneous Environments at Multiple Spatial and Temporal Scales

橡树猝死(SOD)是由类真菌疫霉引起的，是包括栗疫和荷兰榆病在内的一系列外来森林疾病中最新的一种。在过去的10年里，加利福尼亚州和俄勒冈州沿海森林中数以百万计的油橡树和橡树可能已经被超氧化物歧化酶抢走。该项目将审查最初导致丛枝病菌出现的环境和生物环境，以及随后与疾病有关的森林环境变化。我们将采用田间、温室和实验室实验相结合的方法，结合地理信息系统(GIS)和数学建模方法来研究超氧化物歧化酶的时空动态。该项目将研究人类引起的森林景观结构和组成的变化与天气模式(例如厄尔尼诺现象)相结合时，可能如何影响病原体在加州森林中的建立和传播。白粉病入侵后，病原菌、寄主和森林环境也会发生变化。兰花疫霉是一种通用病原菌，可侵染蕨类、裸子植物、单子叶植物和双子叶植物等45个属的植物。加州森林中的草皮流行病主要是由这些相关寄主物种的存在推动的，这些寄主物种是病原体的来源，而不是橡树本身。由于死亡率通常仅限于橡树和橡树，因此广泛的寄主范围将使我们能够检验由病原体介导的植物竞争假说。病原菌的广泛寄主范围也可能使P.ramorum种群朝着更强的毒力和/或更多的多样性进化。然而，随着时间的推移，我们也可以预料到P.ramorum的入侵将影响抗性和耐性寄主基因型的发生和空间分布。最后，寄生虫在影响生态系统功能(例如，养分循环)方面的作用常常被忽视。在与红松相关的覆盖层死亡显著影响沿海森林组成的地区，我们将分析森林地上部分输入、有机质、分解速率和氮素动态的变化。更好地了解通用病原体的入侵过程和影响，对于制定管理和监管战略以保护自然生态系统至关重要。这项研究将在疾病政策和管理、公共宣传和教育方面产生一些广泛的影响。更好地了解通用病原体的入侵过程和影响，对于制定管理和监管战略以保护自然生态系统至关重要。PIS积极参与向州、联邦(APHIS)和国际委员会提供关于超氧化物歧化酶和其他森林疾病的建议。在任何试图被隔离的真菌病原体中，P.ramorum拥有最广泛的宿主范围，并将作为对未来病原体引入的反应的模型。该项目还将支持4名研究生、3名博士后和一些本科生的教育。每个实验室都有包括代表性不足的小组的历史。作为他们教育的一部分，博士后和研究生将参与公共宣传努力。先前存在的关于超氧化物歧化酶研究和管理的合作将继续与北加州的几个美洲原住民部落(Pomo、Hoopa和Yurok)进行。

Sudden Oak Death (SOD), caused by the fungal-like pathogen Phytophthora ramorum, is the latest in a long line of exotic forest diseases that includes chestnut blight and Dutch elm disease. Potentially millions of tanoak and oak trees in coastal forests of California and Oregon have been lost to SOD over the past 10 years. This project will examine the environmental and biological circumstances that initially led to the emergence of P. ramorum and the subsequent disease-related changes to the forest environment. We will use a combination of field, greenhouse, and laboratory experiments along with geographical information system (GIS) and mathematical modeling approaches to research the spatial and temporal dynamics of SOD. The project will examine how human-induced changes in landscape structure and composition of forests when combined with weather patterns (e.g., El Nino) may have influenced the establishment and spread of pathogen in California forests. Following P. ramorum invasion, changes may also occur to the pathogen, host and forest environment. P. ramorum is a generalist pathogen that infects plants in over 45 genera including ferns, gymnosperms, monocots and dicots. SOD epidemics in California forests are primarily driven by the presence of these associated host species that serve as sources of the pathogen, and not by the oaks themselves. Because mortality is often restricted to oak and tanoak, the broad host range of P. ramorum will allow us to test hypotheses of plant competition mediated by a pathogen. The broad host range of the pathogen may also allow for P. ramorum populations to evolve towards increased virulence and/or increased diversity. However, over time we would also expect that invasion by P. ramorum will influence the occurrence and spatial distribution of resistant and tolerant host genotypes. Finally, the role of parasites in influencing ecosystem functioning (e.g., nutrient cycling) has often been overlooked. In areas where P. ramorum-associated overstory mortality has significantly impacted composition of coastal forests, we will analyze changes in forest floor inputs, organic matter, decomposition rates, and nitrogen dynamics. A better understanding of invasion processes and impacts of generalist pathogens is critical for developing management and regulatory strategies to protect natural ecosystems. This research will have a number of broad impacts in disease policy and management, publicoutreach, and education. A better understanding of invasion processes and impacts of generalist pathogens is critical for developing management and regulatory strategies to protect natural ecosystems. The PIs are actively involved with advising state, Federal (APHIS) and International committees on SOD and other forest diseases. P. ramorum has the broadest host range of any fungal pathogen ever attempted to be quarantined and will serve as a model for responses to future pathogen introductions. The project will also support the education of 4 graduate students, 3 post-docs as well as a number of undergraduate students. Each lab has a history of including under-represented groups. As part of their education, post-docs and graduate students will be involved in public outreach efforts. Pre-existing collaborations on research and management of SOD will be continued with several Native American tribes (Pomo, Hoopa, and Yurok) in Northern California.