18-BTT EAGER: Controlling meiotic recombination in crops by manipulating DNA methylation

该联盟计划开发高度创新的战略，以刺激基因组区域的重组，这些区域通常难以应对关键作物物种的遗传变异。在低重组率的基因组区域开发提高重组率的方法将有助于更有效的育种。这一成果将缩短开发新的优良种质所需的时间，并能够快速导入来自不同来源的可取基因，以促进开发出更健壮的作物，这些作物将以可持续的方式展示出优越的生产力，并更适合于应对气候变化带来的挑战。这个项目的目标是了解DNA甲基化是如何影响植物减数分裂重组的。减数分裂重组是由染色体DNA中许多程序性双链断裂启动的，其中一小部分被处理以形成交叉。因此，由单轮减数分裂重组产生的遗传变异是有限的。此外，在拥有大基因组的植物(包括大多数作物)中，交叉的分布高度偏向于染色体末端。因此，广泛的间质和着丝粒近端染色体区域很少重组。然而，这些巨大的基因组区域包含大约五分之一的玉米基因，以及其他一些作物甚至更大的基因片段，这给植物育种带来了严重的障碍。最近的研究表明，DNA甲基化是形成交叉景观的关键因素。然而，重组和DNA甲基化之间的确切关系还不清楚。该项目旨在阐明DNA甲基化如何在机制水平上影响重组模式，并为通过改变DNA甲基化来控制作物交叉景观的方法奠定基础。这项研究将在玉米和油菜中进行，以探索单子叶和双子叶基因组的行为。为了阐明DNA甲基化对减数分裂重组的影响，将开发一种在减数分裂过程中瞬时改变DNA甲基化模式的方案。这些化学去甲基化的植物和选定的DNA甲基化缺陷突变株将用于确定DNA甲基化改变了减数分裂的哪些步骤和过程。还将确定DNA甲基化的哪个特定方面会影响交叉景观。

This consortium plans to develop highly innovative strategies to stimulate recombination in genomic regions that are normally refractory to genetic variation in key crop species. Developing ways to increase recombination rates in genome areas of low recombination will contribute to more efficient breeding. The outcome will allow reducing the time required to develop new elite germplasm and enable rapid introgression of desirable genes from diverse sources to facilitate developing more robust crops that will exhibit superior productivity in sustainable ways and be better suited to deal with the challenges arising from the climate change. The goal of this project is to gain an understanding of how DNA methylation influences the meiotic recombination landscape in plants. Meiotic recombination is initiated by the formation of numerous programmed double-strand breaks in chromosomal DNA, a small proportion of which are processed to form crossovers. Thus, genetic variation generated by a single round of meiotic recombination is limited. Furthermore, the distribution of crossovers in plants with large genomes, which include most crops, is highly biased towards the ends of chromosomes. As a result, extensive interstitial and centromere proximal chromosome regions rarely recombine. Yet, these large genome areas contain roughly one-fifth of the genes in maize and even larger gene fractions in some other crops, which presents a serious impediment to plant breeding. Recent studies indicate that DNA methylation is a critical factor shaping crossover landscapes. However, the exact relationship between recombination and DNA methylation is not understood. This project seeks to elucidate how DNA methylation affects recombination patterns at the mechanistic level and lay foundations for methods to control crossover landscapes in crops by altering DNA methylation. The study will be conducted in maize and Brassica rapa, to explore the behavior of both monocot and dicot genomes. To elucidate the effect of DNA methylation on meiotic recombination, a protocol to transiently alter DNA methylation patterns in meiosis will be developed. The chemically demethylated plants and selected mutants defective in DNA methylation will be used to determine which steps and processes of meiosis are altered by DNA methylation. It will be also established which specific aspect of DNA methylation affects crossover landscape.