Genomic Analysis of a Nematode-plant Interaction: A Tool to Study Plant Biology

线虫与植物相互作用的基因组分析：研究植物生物学的工具

• 批准号: 0077503
• 负责人: David Bird
• 金额: $ 260.78万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0077503&HistoricalAwards=false
• 关键词: Genomic; Analysis; Nematode; plant; Interaction

Plant-parasitic nematodes reduce annual US agricultural production by more than $5 billion. The most important group are the root-knot nematodes (RKN: Meloidogyne spp.), which are devastating pathogens of food and fiber crops. With the loss of chemical control agents for health and environmental reasons, the economic importance of RKN is increasing world-wide. A prerequisite to developing any new, environmentally-safe and affordable control strategy is a thorough understanding of the biology of the plant-nematode interaction. Recent advances in genomic techniques make this previously intractable host-parasite system amenable to study. Because of the intimate nature of the interaction, and the obvious developmental and physiological perturbations to the host induced by the nematode, understanding the biology of this association will shed new light on basic plant processes. The very broad host range of RKN (excess of 2,000 plant species) implies that this parasite is able to modulate some very fundamental and widely conserved aspect of host biology.RKN hatch in the soil as developmentally-arrested larvae prior to invading a root, where the parasite establishes an intimate relationship with its host. An elaborate permanent feeding site, characterized by the formation in the host of "giant cells" within a gall, is induced by the nematode. Giant cells serve as the obligate nutritive source for the developing nematode, which becomes sedentary. Functional genomic approaches will be applied to analyze this interaction. This approach is feasible because well developed models of the host and parasite (Arabidopsis and C. elegans respectively) have been established, including complete genomic sequences.Suites of nematode and plant genes that define pathways for establishment of the parasitic interaction will be identified, and their expression quantified. Host responses during feeding-site formation, and the biological transitions in the nematode that are coupled to the host (e.g., exit from developmental-arrest at the onset of feeding) are especially interesting. The histology suggests that phyto-hormone levels are altered in infected roots, and expression of Arabidopsis gene sets, with an emphasis on hormone-responsive genes (new members of this class are anticipated to be identified) will be quantified, as well as genes previously identified as being specifically nematode-responsive. This project addresses three general and inter-related scientific questions: 1) how is the host recognized, and how does the parasite couple its biology and development to host cues, 2) what are the parasite-induced changes in the host, and in particular what is the source and role of phyto-hormones, 3) how has parasitism evolved, what has been the role of horizontal gene transfer, and is this reflected in the organization of parasitism genes?A large body of mostly descriptive information exists for RKN and an important goal will be to couple the genomic findings with this biological data. Many features of the RKN-plant interaction (e.g., gall formation) appear canonical for a broad range of host-parasite associations involving diverse organism (including insects), and also represents a tractable model to study aspects of normal plant development, including phyto-hormone biosynthesis/regulation. Better understanding the host-parasite interaction will reveal the linch-pins from which novel nematode-management strategies can be derived. Furthermore, because this research will be performed within a framework of graduate and undergraduate education, it will provide students with significant opportunities for professional development.

植物寄生线虫每年使美国农业产量减少50多亿美元。最重要的一类是根结线虫（RKN：根结线虫属），它们是粮食和纤维作物的毁灭性病原体。由于健康和环境原因，化学控制剂的损失，RKN的经济重要性在世界范围内不断增加。开发任何新的，环境安全和负担得起的控制策略的先决条件是彻底了解植物-线虫相互作用的生物学。基因组技术的最新进展，使这个以前棘手的主机寄生虫系统适合研究。由于这种相互作用的亲密性质，以及由线虫引起的对宿主的明显发育和生理扰动，理解这种关联的生物学将为植物的基本过程提供新的线索。RKN的宿主范围非常广泛（超过2，000种植物物种），这意味着这种寄生虫能够调节宿主生物学的一些非常基本和广泛保守的方面。RKN在侵入根部之前在土壤中孵化为发育停滞的幼虫，寄生虫在根部与其宿主建立亲密关系。一个精心设计的永久性的进食场所，其特征是在宿主的胆汁内形成“巨细胞”，由线虫诱导。巨细胞作为专性营养源的发展线虫，成为定居。功能基因组学方法将被应用于分析这种相互作用。这种方法是可行的，因为宿主和寄生虫（拟南芥和C。线虫和植物的基因组序列已经确定，包括完整的基因组序列。确定建立寄生虫相互作用途径的线虫和植物基因组将被鉴定，它们的表达将被量化。 在取食位点形成期间的宿主反应，以及线虫与宿主偶联的生物学转变（例如，在进食开始时从发育停滞中退出）是特别有趣的。组织学表明，植物激素水平的改变，在受感染的根，和拟南芥基因集的表达，重点是线虫响应基因（这一类的新成员预计将被确定）将被量化，以及基因先前确定为特异性线虫响应。该项目涉及三个相互关联的一般性科学问题：1）宿主是如何被识别的，寄生虫如何将其生物学和发育与宿主线索相结合，2）寄生虫引起的宿主变化是什么，特别是植物激素的来源和作用，3）寄生是如何进化的，水平基因转移的作用是什么，这是否反映在寄生基因的组织中？RKN存在大量的描述性信息，一个重要的目标是将基因组发现与此生物学数据相结合。RKN-植物相互作用的许多特征（例如，虫瘿形成）对于涉及不同生物体（包括昆虫）的广泛的宿主-寄生物关联似乎是典型的，并且还代表了研究正常植物发育的各个方面（包括植物激素生物合成/调节）的易处理的模型。更好地了解宿主-寄生虫相互作用将揭示新的线虫管理策略的关键。此外，由于这项研究将在研究生和本科教育的框架内进行，它将为学生提供专业发展的重要机会。