Evolution of organismal composition and architecture in self-assembling fungal symbioses

大多数形式的多细胞，多区域共生涉及依赖于微生物伙伴的大型，结构上确定的宿主。相比之下，一些共生体拥有只有全微观共生体才能实现的身体计划。地衣就是这种情况，它是一种基于真菌和光合作用伙伴（通常是单细胞藻类或蓝藻）之间相互作用的共生结构。这些伴侣在显微镜下相当于线状（真菌菌丝）和球状（单细胞藻类），它们不能自己形成地衣。宏观结构是由特定基序的细胞外聚合物粘合在一起的伙伴细胞所影响的，本质上是3D生物膜。然而，“线”上的细胞有相互连接的细胞质，而“球”表面上是独立的。它们如何形成具有保守模式和尺寸的宏观地衣尚不清楚。我的研究使用现代工具对地衣生物学的一些最基本假设进行了压力测试，这些假设在150年来基本上没有受到过挑战。应用散弹枪DNA、RNA和蛋白质测序揭示，在单个地衣中发现的核心有机组合总是比教科书中介绍的两个多。其他真菌和细菌似乎是恒定的组成部分。然而，识别之前被忽视的微生物的功能反过来需要重新审视我们对地衣身体计划和将其结合在一起的胶水的基本理解。我的DG致力于三个主要目标领域，旨在显著缩小这些知识差距：核心共生体如何在地衣体系结构中变化？我将使用宏基因组学来绘制核心共生体在结构多样化的地衣群体进化过程中的变化。我将比较个体基因组，以了解基因家族是如何随着共生体发生的地衣而变化的。最后，我将使用共聚焦激光显微镜在原位观察共生体。什么是维持地衣共生体的细胞外基质？我将使用用于研究生物膜的特定染色方法研究细胞外聚合物组成，以及基质蛋白质组和糖的靶向取样。哪些核心共生体促成了这一层的形成？我将利用我们对地衣次生代谢物的生物合成途径的知识来可视化哪些参与者参与了同位素标记前体的合成并生产了这些代谢物。与我的平行目标领域一起，这将是一种将基因组直接与整个共生体组合的商品和服务池联系起来的强大方法。我正在开发的方法和途径与理解复杂的真核-原核生物膜系统直接相关。我专注于破解这个复杂系统中的给予和接受，将为理解在生物膜样环境中相互作用的其他共生系统提供突破口。

Most forms of multicellular, multi-domain symbiosis recognized today involve large, structurally defining hosts dependent on microbial partners. Some symbioses, by contrast, possess body plans that are only achieved with all-microscopic symbionts. This is the case with lichens, symbiotic architectures based on interplay between a fungal and a photosynthesizing partner, usually single-celled algae or cyanobacteria. The partners are the microscopic equivalent of string (fungal hyphae) and balls (unicellular algae), and unable to form lichens on their own. The macroscopic architecture is effected by the gluing together of partner cells by extracellular polymers in specific motifs, essentially 3D biofilms. However, the cells along the "string" have interconnected cytoplasms and the "balls" are ostensibly autonomous. How they form a macroscopic lichen with conserved patterns and dimensions is unknown. My research uses modern tools to stress-test some of the most basic assumptions of lichen biology, assumptions that have been essentially unchallenged for 150 years. Application of shotgun DNA-, RNA- and protein sequencing has revealed that the core organismal assemblage found in a single lichen is invariably more than the twosome presented in textbooks. Additional fungi as well as bacteria appear to be constant components. However, identifying the functions of the previously overlooked microbes in turn requires revisiting our basic understanding of the lichen body plan and the glue that holds it together. My DG is dedicated to three main goal areas that aim to significantly close these knowledge gaps: How do core symbionts change across lichen architectures? I will use metagenomics to map changes in core symbionts over the evolution of an architecturally diverse group of lichens. I will compare individual genomes to understand how gene families changed along with the lichen in which the symbiont occurs. Finally, I will use confocal laser microscopy to visualize the symbionts in situ. What is the extracellular matrix that holds lichen symbionts in place? I will investigate extracellular polymer composition using specific staining approaches used in study biofilms, as well as targeted sampling of the matrix proteome and glycome. Which core symbionts contribute to this forming this layer? I will leverage our knowledge of biosynthetic pathways for lichen secondary metabolites to visualize which players are engaged in incorporating isotope-labeled precursors and producing these metabolites. Together with my parallel goal areas, this will be a powerful method of directly tying genomes to the goods and services pool of the total symbiont assemblage. The methods and approaches I am developing are at directly relevant to understanding complex eukaryote-prokaryote biofilm systems. My focus on cracking the give and take in this complex system will provide inroads for understanding other symbiotic systems that interact in biofilm-like contexts.