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

该联盟计划开发高度创新的策略，以刺激基因组区域的重组，这些区域通常不受关键作物物种遗传变异的影响。开发提高低重组基因组区域重组率的方法将有助于更有效的育种。这一成果将减少开发新的优良种质所需的时间，并使来自不同来源的理想基因能够迅速渗入，以促进开发更健壮的作物，这些作物将以可持续的方式表现出上级生产力，并更适合应对气候变化带来的挑战。这个项目的目标是了解DNA甲基化如何影响植物减数分裂重组景观。减数分裂重组是通过在染色体DNA中形成许多程序性双链断裂来启动的，其中一小部分被加工以形成交换。因此，由单轮减数分裂重组产生的遗传变异是有限的。此外，在包括大多数作物的具有大基因组的植物中，杂交的分布高度偏向于染色体的末端。因此，广泛的间质和着丝粒近端染色体区域很少重组。然而，这些大的基因组区域包含了玉米中大约五分之一的基因，在其他一些作物中甚至更大的基因片段，这对植物育种构成了严重的障碍。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尚不清楚。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甲基化控制作物交叉景观的方法奠定基础。该研究将在玉米和芜菁中进行，以探索单子叶植物和双子叶植物基因组的行为。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中瞬时改变DNA甲基化模式的方案。化学去甲基化的植物和选择的DNA甲基化缺陷突变体将用于确定减数分裂的哪些步骤和过程被DNA甲基化改变。还将确定DNA甲基化的哪个特定方面影响交叉景观。

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.