EF: Ecological Genetics of Host-Specific Species Formation

EF：宿主特异性物种形成的生态遗传学

• 批准号: 0315946
• 负责人: William Starmer
• 金额: $ 38.77万
• 依托单位: Syracuse University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0315946&HistoricalAwards=false
• 关键词: EF; Ecological; Genetics; Host; Specific

Ecological Genetics of Host-Specific Species FormationWilliam T. Starmer and Scott E. ErdmanSyracuse UniversityThe central goal of the research is to integrate knowledge of the ecology and genetics of microorganisms in a single system to understand the mechanisms responsible for formation of new species. The project will focus on fungal speciation mechanisms and target two closely related yeast species that live in different types of columnar cacti in the Sonoran Desert. The two yeasts, within the Pichia amethionina complex, only live in rotting stems of cacti and have close ecological associations with other cactus-specific yeasts and drosophila. The two cactus types (Stenocereus and Pachycereus) differ from one another in their stem chemistry. Earlier investigations have demonstrated that an abundant natural product in the form of a triterpene glycoside is found only in Stenocereus species and inhibits growth of one of the yeast species, thus preventing it from growing in that cactus. Genetic studies have shown the inhibition to be due to at least one gene difference between the two cactus dwelling yeast species. A genome-wide knockout library of the common baker's yeast Saccharomyces cerevisae is being employed by this project to identify and study candidate genes that may be identical to the cactus-yeast genes responsible for the species diversification in the Pichia amethionina complex. In general, identification of candidate genes, in the whole genome, provides information on potential physiological function when challenged with the host chemicals and thus an overview of potential cellular effects experienced by the yeast in the natural environment.There are four phases of the research: 1) Catalog all genes that can provide resistance to the triterpene glycosides. This work will be done using modern yeast genetic tools and knowledge of the genomics of S. cerevisae. 2) Determine which genes in the catalog can confer resistance in the cactus-yeast. This work will utilize insertional mutagenesis and expression vectors as tools. 3) Determine which genes that can confer resistance actually do confer resistance in nature. This work will use field surveys and standard laboratory genetic crosses to find the actual genes responsible. 4) Discover the ecological reasons (limits and constraints) that restrict the possible solutions to the actual solutions found in nature. Ecological experimentation in the laboratory using cactus tissue, drosophila, and associated yeasts will be used to find the connection between the ecology and genetics responsible for the actual solution and diversification.The project will be significant to our understanding of fundamental processes involved in the formation of new species. Detailed molecular mechanisms in relation to ecological constraints will provide a unique view of how microorganisms adapt to novel and exotic chemicals in their natural environment and why some genetic solutions are employed more frequently or with preference relative to others.

宿主特异性物种形成的生态遗传学威廉·T·斯塔默和斯科特·E·埃德曼雪城大学这项研究的中心目标是将微生物的生态学和遗传学知识整合到一个系统中，以了解新物种形成的机制。该项目将重点研究真菌物种形成机制，并针对生活在索诺兰沙漠不同类型柱状仙人掌中的两种密切相关的酵母物种。 这两种酵母属于氨基甲硫氨酸毕赤酵母复合体，仅生活在仙人掌的腐烂茎中，并与其他仙人掌特异性酵母和果蝇具有密切的生态联系。 两种仙人掌类型（狭角仙人掌和厚角仙人掌）的茎化学成分不同。 早期的研究表明，仅在狭角仙人掌属物种中发现了丰富的三萜糖苷形式的天然产物，并抑制其中一种酵母菌的生长，从而阻止其在仙人掌中生长。 遗传学研究表明，这种抑制是由于两种仙人掌酵母物种之间至少存在一种基因差异所致。 该项目正在利用常见面包酵母酿酒酵母的全基因组敲除文库来识别和研究候选基因，这些候选基因可能与负责氨基甲硫氨酸毕赤酵母复合体中物种多样化的仙人掌-酵母基因相同。一般来说，在整个基因组中识别候选基因可以提供有关宿主化学物质挑战时潜在生理功能的信息，从而概述酵母在自然环境中经历的潜在细胞效应。研究分为四个阶段：1）对所有可以提供三萜糖苷抗性的基因进行编目。 这项工作将利用现代酵母遗传工具和酿酒酵母基因组学知识来完成。 2) 确定目录中的哪些基因可以赋予仙人掌酵母抗性。 这项工作将利用插入诱变和表达载体作为工具。 3) 确定哪些可以赋予抗性的基因实际上确实赋予了自然界抗性。 这项工作将使用实地调查和标准实验室遗传杂交来找到真正负责的基因。 4）发现限制可能的解决方案到自然界中发现的实际解决方案的生态原因（限制和约束）。 在实验室中使用仙人掌组织、果蝇和相关酵母进行生态实验，将用于寻找负责实际解决方案和多样化的生态学和遗传学之间的联系。该项目对于我们理解新物种形成所涉及的基本过程具有重要意义。 与生态限制相关的详细分子机制将为微生物如何适应自然环境中的新型和外来化学物质以及为什么某些遗传解决方案被更频繁地使用或相对于其他解决方案优先使用提供独特的视角。