The Evolution of Genetic Systems in Plants

遗传变异的组织和起源，以及它从亲代传递给后代的方法（“遗传系统”）是理解进化过程和农业改进的核心。舍恩实验室的研究重点是野生和栽培植物物种的遗传系统，重点是防止近亲繁殖和保持遗传多样性的机制的进化。我们特别感兴趣的是自不相容（SI）的进化及其丧失，导致自相容（SC）。SI的进化和丧失提供了一个框架，在这个框架中可以检查进化中反复出现的模式和过程。结合这项研究，我们正在研究表观遗传变异是如何在人群中产生的，它是如何维持的，以及表观遗传变异的适应性后果。******我们将继续研究SI的进化和丧失，通过研究如何清除近交抑制（SI进化丧失的主要障碍，也是作物产量的主要决定因素）。这项工作将与近交抑制结构的基因组水平分析相结合，这将提供有关近交抑制的基因座数量和显性水平的信息。与此相关，我们将进行研究，以确定新进化的s位点基因是否可以在现有（非SI相关）植物信号通路的背景下发挥作用，从而产生SI表型，从而帮助解释这种复杂的表型是如何由单个组分组装而成的。******最近的研究结果表明，要全面理解遗传系统在进化变化中的作用，现在必须包括表观遗传修饰。为了提高我们对表观遗传变异的进化意义的理解，我们将在遗传系统研究中使用的方法的基础上，即理论模型和实验的应用。表观遗传修饰进化的群体遗传模型将旨在了解促进该系统在植物中进化的因素，并有助于解释植物（与后生动物相比）表观遗传变异的跨代遗传的明显普遍性。实验研究将采用群体基因组方法和环境操纵，旨在研究表观遗传修饰是如何诱导和遗传的，测试它是否有助于适应性，以及全基因组调查，以扫描过去表观遗传变异选择的基因组特征。******本文提出的工作将培养3名博士生、2名硕士生、1名研究助理和6名本科生研究助理，并将在一定程度上补充我们旨在将SI作为育种工具的应用研究（我们将单独资助）

The organization and origin of genetic variation, together with its method of transmission from the parental generation to progeny generations (the “genetic system”) is central to understanding the evolutionary process and to agricultural improvement. Research in the Schoen lab focuses on genetic systems of both wild and cultivated plant species, with emphasis on the evolution of the mechanisms by which inbreeding is prevented and genetic diversity is maintained. We are particularly interested in the evolution of self-incompatibility (SI) and its loss, leading to self-compatibility (SC). The evolution and loss of SI provides a framework in which to examine recurrent patterns and processes in evolution. Coupled with this investigation, we are examining how epigenetic variation arises in populations, how it is maintained, and the fitness consequences of epigenetic variation.******We will continue work on the evolution and loss of SI by conducting research directed at examining how inbreeding depression (the major barrier to the evolutionary loss of SI, and a major determinant of crop yield), is purged. This work will be coupled with genomic level analyses of the architecture of inbreeding depression that will provide information on the number and dominance level of loci underlying inbreeding depression. Related to this, we will conduct studies to determine whether newly evolved S-locus genes can function within the context of existing (non-SI related) plant signaling pathways to give rise to the SI phenotype, and thus help explain how this complex phenotype is assembled from individual components.******Recent findings suggest that a complete understanding of the role of genetic systems in evolutionary change must now include epigenetic modification. To improve our understanding of the evolutionary significance of epigenetic variation, we will build upon approaches used in our research on genetic systems, namely the application of both theoretical models and experiments. Population genetic modelling of the evolution of epigenetic modification will be aimed at understanding the factors that promote the evolution of this system in plants and help explain the apparent prevalence in plants (compared to metazoans) of transgenerational inheritance of epigenetic variation. Experimental studies will employ population genomic approaches and environmental manipulation aimed at examining how epigenetic modification is induced and inherited, tests for whether it contributes to fitness, and whole genome investigations to scan for genomic signatures of past selection of epigenetic variation. ******The work proposed here will lead to the training of 3 Ph.D. students, 2 M.Sc. students, a Research Associate, and 6 undergraduate research assistants, and will complement, in part, our applied research aimed at using SI as a breeding tool (and for which we are separately funded).**