NSF Postdoctoral Fellowship in Biology FY 2017: Mites, microbes, and fungal pathogens: the ecology and evolution of an indirect defense trait

这是NSF生物学博士后研究奖学金，根据扩大生物学中代表性不足的群体的参与计划。这位名叫Ash Zemenick的研究员正在进行研究并接受培训，以增加生物学中代表性不足的群体的参与。这位研究员正在密歇根州立大学接受马乔里·韦伯的指导。本研究探讨了螨类对植物病原菌的影响。许多植物的叶子上有一小簇毛（domatia），可以容纳螨虫。螨可以通过减少病原体（细菌和真菌）的成功而使植物受益，但其变异的机制和程度尚不清楚。螨可以直接通过食用病原体来减少病原体的成功。此外，通过影响抑制病原体的微生物的丰度，螨可能间接影响病原体的成功。最后，因为不是所有的植物都有虫囊，螨和/或微生物影响病原体的方式可能因植物物种而异。这位研究员正在使用一项实验来解开这些影响，该实验操纵螨虫对植物的访问以及潜在病原体的发生。这项研究将增加对这些广泛的生态相互作用的理解，并有助于农业生态系统中的可持续病原体管理。该项目还包括两个明确的更广泛的影响，解决一些刻板印象，燃料在生物学的代表性不足。首先，这位研究员经历了作为女性和变性人的生活，因此在指导参与研究的本科生方面起到了榜样作用。其次，他正在开发一个教材库，通过强调研究如何应用于社会问题以及成为生物学家的感觉，使生物学和生物学家人性化。这位研究员使用了生物学家提供的例子，这些生物学家自我认同为STEM中代表性不足的群体的成员（例如种族，民族，性别，收入，国籍，移民身份，认知和身体能力等）。该研究员正在进行操纵实验，以了解螨如何直接（通过消费）和/或间接（通过改变微生物群落组成，减少入侵）影响病原体的成功。来自20种葡萄（葡萄属）的叶将用四种处理进行实验操作。两个（T1和T2）将阻止螨，两个（T3和T4）将有螨。2周后，收获一半的叶子以评估叶子微生物群落。将使用条形码ITS和16 S引物扩增真菌和细菌DNA，并将所得多重扩增子进行Illumina测序。无螨（T1和T2）和螨（T3和T4）叶片微生物群落之间的差异将经验性地证明，domatia栖息螨影响叶片微生物群落结构，因此可能间接影响病原体在葡萄属中的成功。另一半重复样本将留在田间，螨只允许在T2和T4上出现。所有的叶子都会受到白粉病的侵袭。如果螨的存在降低了葡萄属叶的病原体感染，则来自T2-T4的叶将具有比对照（T1）叶更低的白粉病侵染。如果病原体感染的这种减少是通过直接消耗而不是通过修饰的叶微生物群落间接减少，则T2和T4叶将具有比T2叶更低的白粉病侵染。为了评估叶片中微生物群落进化和病原体抗性的模式，将使用多维和一维比较系统发育模型来评估微生物群落组成和结构以及病原体抗性是否与葡萄属物种中的多囊壳存在和大小在进化上相关。如果多囊壳的存在和大小与整个系统的白粉病抗性相关，则将有证据表明：A）多囊壳的选择性环境包括病原体抗性，或B）多囊壳的进化选择丧失直接病原体抗性。

This is an NSF Postdoctoral Research Fellowship in Biology, under the program Broadening Participation of Groups Under-represented in Biology. The fellow, Ash Zemenick, is conducting research and receiving training that is increasing the participation of groups underrepresented in biology. The fellow is being mentored by Marjorie Weber at the Michigan State University. This research explores how mites influence the pathogens of plants. Many plants have small tufts of hairs on the leaf ("domatia") that house mites. Mites can benefit plants by reducing the success of pathogens (bacteria and fungi), but the mechanisms and extent of variation are not well understood. Mites can directly reduce success of pathogens by eating them. Also, by influencing the abundance of microbes that inhibit pathogens, mites may indirectly influence pathogen success. Finally, because not all plants have domatia, the way in which mites and/or microbes influence pathogens may vary across plant species. The fellow is disentangling these effects using an experiment that manipulates the access of mites to plants, and the occurrence of potential pathogens. This research will increase the understanding of these widespread ecological interactions, and contribute to sustainable pathogen management in agroecosystems. This project also includes two explicit broader impacts that address some stereotypes that fuel underrepresentation in biology. First, the fellow has experienced life as a woman and transgender person, and thus serves as a role model in mentoring undergraduates involved in research. Second, the fellow is developing a repository of teaching materials to humanize biology and biologists by highlighting how research applies to societal issues and what it's like to be a biologist. The fellow is using examples provided by biologists that self-identify as members of underrepresented groups in STEM (e.g. in terms of race, ethnicity, gender, income, nationality, immigrant status, cognitive and physical ability, etc.). The fellow is conducting manipulative experiment to understand how mites influence pathogen success directly (via consumption) and/or indirectly (via an altered microbial community composition that is less invasible). Leaves from 20 species of grapes (Vitis) will be experimentally manipulated with four treatments. Two (T1 and T2) will block mites, and two (T3 and T4) will have mites. After 2 weeks, half of all leaves will be harvested to assess leaf microbial communites. Fungal and bacterial DNA will be amplified using barcoded ITS and 16S primers and the resulting multiplexed amplicons will be subject to Illumina sequencing. A difference between no-mite (T1 and T2) and mite (T3 and T4) leaf microbial communities would empirically demonstrate that domatia-inhabiting mites influence leaf microbe community structure, and could therefore indirectly influence pathogen success in Vitis. The other half of replicates will remain in the field, with mites allowed only on T2 and T4. All leaves will be challenged with powdery mildew. If mite presence lowers pathogen infection of Vitis leaves, then leaves from T2-T4 will have lower infestation of powdery mildew than control (T1) leaves. If this reduction in pathogen infection is through direct consumption rather than indirectly through a modified leaf microbe community, then T2 and T4 leaves will have lower powdery mildew infestation than T2 leaves. To evaluate patterns of microbial community evolution and pathogen resistance across leaves, multi- and unidimensional comparative phylogenetic models will be used to assess whether microbial community composition and structure, as well as pathogen resistance, are evolutionarily correlated with domatia presence and size across Vitis species. If domatia presence and size are correlated with powdery mildew resistance across the phylogeny, there will be evidence for either: A) the selective environment for domatia included pathogen resistance, or B) evolution of domatia selected for the loss of direct pathogen resistance.