The Parasitic Plant Genome Project

Pi：James H.Westwood(弗吉尼亚理工学院和州立大学)Copis：Claude de PamPhilis(宾夕法尼亚州立大学；亚奖获得者)，John Yoder(加州大学戴维斯分校，亚奖获得者)和Michael Timko(弗吉尼亚大学，亚奖获得者)寄生植物从自养到异养的进化转变是适应植物生物学的一个非凡例子。吸器就是这方面的中心例子，吸器是寄生植物特有的器官，它穿透宿主，在寄生虫和宿主之间形成一座生理桥梁。在萝卜科的寄生虫中，吸器被认为是从根组织进化而来的，但对负责吸器发育的基因的起源一无所知。此外，不受自养限制的寄生植物物种可能会在形态和生理上表现出实质性的变化，如根和叶质量减少，光合作用机制丧失，但对这些变化对它们基因组的影响知之甚少。该项目将通过对三个相互关联的属的比较基因组分析来解决这些问题，这三个属是：兼性寄生虫(杂色三叶草)、具有光合作用能力的专性寄生虫(Striga Hermonthica)和专性全寄生虫(Orobanche Ramosa)。紧密相关的非寄生虫Mimulus的测序基因组的可用性提供了一个完全自养的外群来进一步加强这一方法。该项目将对代表每个寄生虫物种关键生活期转录产物的cDNA进行测序，根据序列多样性和丰度对表达模式进行粗略的比较分析。序列可以通过项目网站、基因库和植物基因组网络(http://pgn.cornell.edu/help/about.shtml))访问，该网络是正在进行的EST测序项目的跟踪文件和序列的公共储存库。拟议研究的预期更广泛的影响：这些研究为未来详细的比较基因表达分析建立了一个起点，旨在识别与从自养向异养进化转变相关的潜在遗传变化。此外，这项研究有望为杂草寄生物种的管理带来新的见解，如Striga和Orobanche spp.，这些寄生物种在世界大部分地区都是毁灭性的农业害虫。该项目的主要影响将是公开发布一组相关植物的广泛基因序列，这些植物包含巨大的形态和生理多样性。该项目将通过一个项目网站接触寄生植物研究社区，并将寻求在美国人员和需要接受基因组学或生物信息学培训机会的发展中国家的研究人员之间建立交流。希望来自该项目的数据将有助于制定有效的控制战略。

PI: James H. Westwood (Virginia Polytechnic Institute and State University)CoPIs: Claude dePamphilis (Pennsylvania State University; subawardee), John Yoder (University of California-Davis; subawardee), and Michael Timko (University of Virginia; subawardee)The evolutionary transition from autotrophism to heterotrophism by parasitic plants is an extraordinary example of adaptive plant biology. The central example of this is the haustorium, an organ unique to parasitic plants that penetrates the host and forms a physiological bridge between parasite and host. In parasites of the Orobanchaceae, the haustorium is believed to have evolved from root tissue, but nothing is known about the origins of the genes responsible for haustorium development. Furthermore, a parasitic plant species free of the constraints of autotrophy may show substantial changes in morphology and physiology such as reductions in root and leaves mass and loss of photosynthetic machinery, but little is known about the consequences of such changes on their genomes. The project will address these issues using a comparative genomic analysis of three related genera that span the spectrum of parasitism: a facultative parasite (Triphysaria versicolor), a photosynthetically competent obligate parasite (Striga hermonthica), and an obligate holoparasite (Orobanche ramosa). The availability of a sequenced genome for the closely related non-parasite Mimulus provides a fully autotrophic outgroup to further enhance this approach. The project will sequence cDNAs representing transcripts from key life stages of each parasitic species, conduct cursory comparative analysis of expression patterns based on sequence diversity and abundance. Sequences can be accessed through the project website, GenBank and the Plant Genome Network (PGN) (http://pgn.cornell.edu/help/about.shtml) which serves as a public repository for trace files and sequences from ongoing EST sequencing projects. Expected broader impacts of the proposed research: These studies establish a starting point for future detailed comparative gene expression analysis aimed at identifying potential genetic changes associated with the evolutionary transition from autotrophy to heterotrophy. In addition, the research is expected to produce new insights into management of weedy parasitic species such as Striga and Orobanche spp., which are devastating agricultural pests in much of the world. A major impact of this project will be the public release of an extensive set of gene sequences from a group of related plants that encompass an enormous breadth of morphological and physiological diversity. This project will reach out to the parasitic plant research communities through a project website, and will seek to establish exchanges between US personnel and researchers from developing nations who need opportunities for training in genomics or bioinformatics. It is hoped that data from this project will contribute to the development of effective control strategies.