Infection Site-specific Analyses Elucidate Arabidopsis Host Processes and Components Mediating the Sustained Growth and Reproduction of a Compatible Obligate Biotroph

白粉病是一种真菌植物病原体，可感染多种农艺和观赏植物，以及模式植物拟南芥。白粉病（PMs）在植物叶片的上层细胞层（表皮）建立了专门的活跃摄食点，通过它获得所有的营养。它们的生长和繁殖需要活的植物组织，并在感染部位显著调节叶片功能和代谢。利用激光特异性分离PM感染部位的细胞，研究人员发现了新的植物调节因子和过程，这些过程被PM在拟南芥上的持续生长和繁殖所特异性改变。鉴定出67种调节因子，其中的子集在光合作用、冷/脱水反应、植物防御、激素信号传导和细胞周期中发挥已知或推断的作用。研究人员将采用遗传、分子、生化和细胞学方法，根据这些调节剂对PM生长和繁殖以及上述过程的影响来表征和分类这些调节剂。此外，将使用上述方法更详细地探讨其中两个过程。例如，通过显微镜分析，研究人员确定PM感染部位的细胞周期发生了改变。具体来说，在受感染的表皮细胞下的细胞中，染色体DNA的拷贝数显著增加。此外，这种增加的拷贝数是维持真菌的充分生长和繁殖所必需的。研究人员将进一步确定这种真菌诱导的染色体DNA增加的因素及其在拟南芥上PM的持续生长和繁殖中的作用。这项研究不仅将为受pm影响的重要经济植物的转化研究确定目标，而且确定的基因和过程也可能影响其他需要活的植物组织和/或建立高度本地化的取食点的微生物。此外，这种高度定位的pm诱导系统应该允许研究人员揭示控制基本过程的调节机制，如细胞周期，这是使用传统方法难以探索的。两名博士后学者和四名本科生，包括在科学领域代表性不足的学生，将在这个跨学科项目中接受培训。与当地公立小学学生的接触将以植物和学校园艺项目为切入点，提高他们的科学素养和探究能力。

Powdery mildews are fungal plant pathogens that infect a variety of agronomic and ornamental species, as well as the model plant Arabidopsis thaliana. Powdery mildews (PMs) establish specialized active feeding sites in the upper cell layer (epidermis) of the plant leaf through which they acquire all their nutrients. They require living plant tissue for their growth and reproduction and dramatically modulate leaf function and metabolism at the site of infection. Using lasers to specifically isolate only those cells at the site of PM infection, the investigators identified novel plant regulators and processes specifically altered by the sustained growth and reproduction of the PM Golovinomyces orontii on A. thaliana. Sixty-seven regulators were identified with subsets of these playing known or inferred roles in photosynthesis, cold/dehydration responses, plant defense, hormone signaling, and the cell cycle. The investigators will employ genetic, molecular, biochemical, and cytological approaches to characterize and classify these regulators based on their impact on PM growth and reproduction and the above processes. Furthermore, two of these processes will be explored in more detail using the above approaches. For example, using microscopic analysis, the investigators determined that the cell cycle is altered at the site of PM infection. Specifically, the number of copies of chromosomal DNA is dramatically enhanced in the cells underlying the infected epidermal cell. Furthermore, this increased copy number is required to maintain the full growth and reproduction of the fungus. The investigators will further define the factors responsible for this fungal-induced increase in chromosomal DNA and its role in the sustained growth and reproduction of the PM on Arabidopsis. Not only will this research identify targets for translational research in economically important plants impacted by PMs, but identified genes and processes may also impact other microbes that require living plant tissue and/or establish highly localized feeding sites. In addition, this highly localized, PM-inducible system should allow the investigators to uncover regulatory mechanisms governing fundamental processes, such as the cell cycle, that are challenging to explore using traditional approaches. Two postdoctoral scholars and four undergraduates, including students underrepresented in the sciences, will be trained in this interdisciplinary project. Outreach to students of local public elementary schools will enhance scientific literacy and inquiry using plants and school gardening programs as accessible entry points.