Releasing natural variation in bread wheat by modulating meiotic crossovers

在面包小麦中，重要的农艺性状沿着染色体分布。传统上，植物育种者杂交高产亲本系，然后在随后的世代中选择携带期望的属性同时去除不期望的性状的后代。然而，“基因改组”（减数分裂重组）的过程是非随机的，并偏向染色体的末端。因此，期望的特性通常与不期望的特性一起作为块传输。这类似于处理一副牌，其中很大一部分牌由弹性带拴系。在这种情况下，直到弹性带被切断并且卡片能够自由地分离，才能获得期望的手感。在这项提案中，我们的目标是了解为什么面包小麦中的理想和不理想的性状经常联系在一起，以便我们可以打破这种联系，并释放可用的自然变异的全部潜力。然后，我们的目标是调整这一过程，使植物育种者可以决定哪些性状可以在同一品种中一起“处理”。这种对小麦自然变异的解锁将导致通过经典植物育种产生具有有利农艺性状（例如增加产量和改善养分获取）的上级品种。为了提供我们的研究具有应用性的直接证据，我们将与英国最大的两个小麦育种公司KWS和RAGT合作，以染色体区域为目标，这些区域已知是作为块传播的。我们将表明，通过使用新的程序，我们可以增加这些块中的重组量。增加这些区域中任何一个区域的重组量将使育种者能够产生新的基因组合，这将导致具有例如增加的蛋白质含量或病原体抗性的新品种。在育种者的管道中，我们的研究将直接转化为具有上级特性的新品种，这将有助于维持农业收入并提高英国耕地和碾磨业的可持续性。此外，高产品种将减少对进口谷物的依赖以及相关的运输和环境成本，并改善生产新的英国品种的管道，这将提高海外市场的可靠性和竞争力。

In bread wheat, important agronomical traits are distributed along chromosomes. Traditionally, plant breeders cross high yielding parental lines and then select for progeny in subsequent generations that carry desirable attributes whist removing undesirable traits. However, the process of 'gene-shuffling' (meiotic recombination) is non-random and skewed towards the ends of the chromosomes. Therefore, desirable traits are often transmitted as a block together with undesirable traits. This is analogous to dealing a deck of cards where a significant proportion of the cards are tethered by an elastic band. In this case a desirable hand cannot be achieved until the elastic band is severed and the cards are able to segregate freely. In this proposal we aim to understand why desirable and undesirable traits in bread wheat are often tethered together, so that we can break this bond, and release the full potential of available natural variation. Then, we aim to modulate this process so that the plant breeder can decide which traits can be 'dealt' together in the same variety. This unlocking of wheat's natural variation will lead to the production, via classical plant breeding, of superior varieties with favourable agronomic traits such as increased yield and improved nutrient acquisition. To provide direct evidence that our research has application we will work with two of the UK's largest wheat breeders KWS and RAGT to target chromosomal regions, which are known to be transmitted as blocks. We will show that by using novel procedures, we can increase the amount of recombination in these blocks. Increasing the amount of recombination in any of these regions will enable breeders to generate new gene combinations which will lead to new varieties with, for instance, increased protein content or pathogen resistance. Further down the breeder's pipeline our research will directly translate to new varieties with superior characteristics that will help maintain farm incomes and improve sustainability of the UK arable and milling industries. In addition high yielding varieties will reduce dependence on imported grain and associated transport and environmental costs and improved pipelines for the generation of new UK varieties that will enhance reliability and competitiveness in overseas markets.