Dynamics of nuclear-mitochondrial interactions in the canola plant Brassica napus

油菜植物甘蓝型油菜中核-线粒体相互作用的动态

• 批准号: 7624-2010
• 负责人: Brown, Gregory
• 金额: $ 2.4万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=474250
• 关键词: Dynamics; nuclear; mitochondrial; interactions; canola

The genetic interaction between pathogens and host organisms has led to the concept of a genetic arms race: genes evolve in pathogens that allow them to evade host defenses, and in response genes evolve in hosts that allow them to resist such new pathogenic strains. Cytoplasmic male sterility (CMS) is a widespread trait among higher plants that results from the expression of novel open reading frames (ORFs) in mitochondrial DNA (mtDNA). In many cases, nuclear genes termed restorers-of-fertility (Rf) have been identified that suppress the CMS phenotype. Such restorer genes are specific for a particular form of CMS and function by down-regulating the expression of the novel, CMS-associated ORF. CMS can be viewed as a particularly interesting "intra-genomic" type of arms race: maternally inherited CMS-conferring mtDNAs spread in a population due to the selective advantage of not allocating resources into pollen production; as CMS individuals become more frequent, pollen becomes limiting, creating the selective pressure for evolution of new restorers. Studies from my laboratory over the last 15 year have revealed features of CMS / restorer gene systems of the canola plant Brassica napus that suggest these systems may provide a useful insight into this arms race. More recently, we discovered that ORF containing gene arrangements responsible for the two forms of B. napus CMS are present at substoichiometric levels in mitochondria in which they are not expected to occur, including mitochondria of one of the progenitor species of B. napus. In addition, we have now cloned and characterized one form of the Brassica nuclear restorer locus. The proposed studies build on this recent work and may allow us to obtain a comprehensive understanding of how CMS-restorer systems evolve. Specifically, we will determine if alteration mt genomic configurations can lead to amplification of the substoichiometric CMS-associated gene arrangements and male sterility; we will characterize the different forms of the restorer locus to gain insight into the molecular events by which the restorers evolved; and we will identify specific restorer genes and the molecules the proteins they encode interact with.

病原体和宿主生物体之间的遗传相互作用引发了基因军备竞赛的概念：病原体中的基因进化使它们能够逃避宿主的防御，而作为响应，宿主中的基因进化使它们能够抵抗这种新的致病菌株。细胞质雄性不育 (CMS) 是高等植物中普遍存在的性状，是由线粒体 DNA (mtDNA) 中新的开放阅读框 (ORF) 的表达引起的。 在许多情况下，已鉴定出称为生育力恢复基因 (Rf) 的核基因可抑制 CMS 表型。此类恢复基因对特定形式的 CMS 具有特异性，并通过下调新型 CMS 相关 ORF 的表达来发挥作用。 CMS可以被视为一种特别有趣的“基因组内”军备竞赛：由于不将资源分配到花粉生产的选择性优势，母系遗传的赋予CMS的mtDNA在群体中传播；随着 CMS 个体变得更加频繁，花粉变得有限，为新恢复体的进化产生了选择压力。我的实验室过去 15 年的研究揭示了油菜植物甘蓝型油菜的 CMS/恢复基因系统的特征，表明这些系统可能为这场军备竞赛提供有用的见解。最近，我们发现含有负责两种形式的甘蓝型油菜CMS的基因排列的ORF以亚化学计量水平存在于线粒体中，而它们预计不会出现在线粒体中，包括甘蓝型油菜祖先物种之一的线粒体。此外，我们现在已经克隆并鉴定了一种形式的芸苔属核恢复基因座。拟议的研究建立在最近的工作基础上，可能使我们能够全面了解 CMS 恢复系统如何演变。具体来说，我们将确定 mt 基因组构型的改变是否会导致亚化学计量 CMS 相关基因排列的扩增和雄性不育；我们将表征恢复基因座的不同形式，以深入了解恢复基因进化的分子事件；我们将识别特定的恢复基因以及它们编码的蛋白质与之相互作用的分子。