Population genomic studies of mating system transitions

交配系统转变的群体基因组研究

• 批准号: 2700-2012
• 负责人: Schoen, Daniel
• 金额: $ 3.64万
• 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: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=568257
• 关键词: Population; genomic; studies; mating; system

Our lab investigates the evolution and genetics of reproductive systems in plants. This project proposes to extend our knowledge of the evolutionary biology of self-incompatibility systems. Self-incompatibility is the major mechanism by which plants avoid inbreeding. The loss of self-incompatibility is hypothesized to be the first step in the evolution of self-pollination, an evolutionary transition that is among the most common in plants. The proposed research focuses on the genus Leavenworthia, where there have been multiple mating system transitions. It centers on the S-locus, which consists of two tightly linked genes, SRK (which functions in the recognition of self-pollen) and SCR (which codes for a ligand recognized by the SRK product). The locus has recently been cloned in several mustard species, and our lab has extended these results to Leavenworthia. The genome of one species of Leavenworthia (L. alabamica) has recently been sequenced. We propose to build upon this progress to address the following questions: (1) Do S-locus mutations occur at low frequencies in self-incompatible populations? (2) When self-compatibility evolves, is it generally due to mutations in SCR or to mutations SRK? (3) What is the nature and strength of selection on mutations at the S-locus that have given rise to populations with self-compatibility? (4) Why do selfing taxa appear to be short-lived in evolutionary time? We will conduct high throughput re-sequencing of samples from populations, detailed molecular analysis of S-locus mutations, expression analyses of the S-locus, and field experiments. Studies of the genetic basis of selfing have so far been restricted to a few taxa. It is not known to what extent mutations at single loci lead to selfing and what types of mutations are selected. The proposed work will be among the first studies to assess the strength of selection acting on mutations that cause selfing, and to adopt a whole genome level approach to investigating how the evolution of selfing influences genome evolution. The issues addressed are important to understanding the evolution and long-term prospects of selfing taxa, which represent a significant proportion of flowering plants and a disproportionate number of crop species.

我们的实验室研究植物生殖系统的进化和遗传学。该项目旨在扩展我们对自交不亲和系统的进化生物学的了解。 自交不亲和性是植物避免近交的主要机制。 据推测，自花不亲和性的丧失是自花授粉进化的第一步，自花授粉是植物中最常见的进化转变之一。 拟议的研究重点是莱文沃斯属，该属存在多种交配系统转变。 它以 S 基因座为中心，该基因座由两个紧密相连的基因组成：SRK（负责识别自体花粉）和 SCR（编码 SRK 产物识别的配体）。该基因座最近已在几种芥菜物种中被克隆，我们的实验室已将这些结果扩展到莱文沃斯菌。一种莱文沃斯菌（L. alabamica）的基因组最近已被测序。 我们建议在这一进展的基础上解决以下问题：（1）S位点突变在自交不亲和群体中是否以低频率发生？ (2) 当自交亲和性进化时，通常是由于 SCR 突变还是 SRK 突变？ (3) 产生自交亲和性群体的 S 位点突变选择的性质和强度是什么？ (4) 为什么自交类群在进化过程中寿命似乎很短？我们将对群体样本进行高通量重测序、S位点突变的详细分子分析、S位点表达分析以及现场实验。迄今为止，对自交遗传基础的研究仅限于少数分类群。 目前尚不清楚单个基因座的突变在多大程度上导致自交以及选择什么类型的突变。这项拟议的工作将是首批评估选择作用于导致自交的突变的强度的研究之一，并采用全基因组水平的方法来研究自交进化如何影响基因组进化。这些问题对于理解自交类群的进化和长期前景非常重要，自交类群代表了开花植物的很大一部分和作物物种的不成比例的数量。