Genomics Enhanced Wheat Breeding: Using sequencing technologies for trait dissection, marker assisted selection and genomic selection in wheat.

面包小麦占世界粮食的五分之一，是发展中国家蛋白质的主要来源，在这些消费者的饮食中仅次于大米的卡路里来源。它是英国种植最广泛的可耕种作物，每年种植面积约为180万公顷。英国育种者和农民在开发和种植具有更高产量潜力的小麦品种方面取得了巨大成功：从1948年到2006年，英国的平均产量从每公顷约3吨增加到约8.0吨。不幸的是，小麦产量增长没有跟上需求增长的步伐。此外，小麦生产力受到疾病、对高质量农田的竞争、资源限制和恶劣环境条件的威胁，这些因素极大地降低了最佳产量。据估计，欧洲的生产率需要翻一番，以跟上需求的步伐并保持稳定的价格。为了帮助植物育种者改进小麦品种，他们利用了遗传变异，特别是单核苷酸多态(SNPs)，这些变异与已知的性状有关，如抗病、对特定环境的适应、面包制作质量特征和产量构成因素。饲养者使用分子标记来追踪连锁的SNPs，作为这些有益特征的代理。这种方法的优点是可以更快、更便宜地筛选数以千计的品系，在某些情况下，比在田间种植更准确地评估品系。小麦是从两个自然发生的独立杂交事件进化而来的，每个杂交事件都造成了遗传瓶颈。首先，两种野草杂交形成了意大利面小麦的近亲。随后，第三种野草杂交生产面包小麦。因此，基因组总大小约为16,000 Mb，是水稻基因组的35倍，是人类基因组的5倍。面包小麦相对缺乏多样性，导致育种者和研究人员将小麦品种与小麦的近缘杂交，以增加遗传多样性，特别是引入抗病等有益性状。虽然在面包小麦中发现了大量的SNP，但在相对较少的品种中发现了这些SNPs，而且这些SNPs并不总是与育种者工作的特定种质相关。此外，许多与小麦杂交的亲缘关系还没有被识别出特定的SNPs，这对育种者来说是一个‘盲点’。该项目旨在利用一种名为外显子组捕获和‘下一代测序’的技术来产生280个小麦品种的小麦基因的DNA序列数据。这是一个降低复杂性的过程，它减少了基因组的大小，并将使我们能够产生大量线路的序列数据。这些品系将被选中，以包含已杂交到小麦中的关键亲缘关系。这些数据将使我们能够识别我们一直忽视的区域，并更准确地定位感兴趣的基因，这样我们就可以使用分子标记为它们繁衍后代。最终，这将有助于我们开发出对农民具有关键特征的品种，如抗病毒能力，这将使他们能够使用更少的杀虫剂，并更可靠地种植小麦。

Bread wheat accounts for a fifth of the world's food, is the main source of protein in developing countries and is second only to rice as a source of calories in those consumers' diets. It is the most widely grown arable crop in the UK, where it is grown on around 1.8 million hectares per year.UK breeders and farmers have been highly successful in developing and growing wheat varieties with higher yield potential: over the period 1948 to 2006, average yields in the UK increased from ~3 tonnes per hectare to ~8.0 tonnes. Unfortunately, wheat production increases have not kept pace with increased demand. Furthermore, wheat productivity is threatened by disease, competition for high quality agricultural land, resource limitations, and adverse environmental conditions that dramatically reduce optimal yields. It has been estimated that in Europe productivity needs to double to keep pace with demand and to maintain stable prices.To help plant breeders improve wheat varieties they have utilised genetics variants, in particular Single Nucleotide Polymorphisms (SNPs), that are linked to known traits such as disease resistance, adaptation to particular environments, bread making quality characteristics and components of yield. Breeders use molecular markers to track linked SNPs as a proxy for these beneficial traits. This has the advantage of screening many thousands of lines quicker, cheaper, and in some cases more accurately than growing in a field to assess the lines conventionally.Wheat evolved from two naturally occurring separate hybridisation events, each creating a genetic bottleneck. Firstly two wild grasses hybridised to form a relative of pasta wheat. Subsequently a third wild grass hybridised to produce bread wheat. As a result, the total genome size is approximately 16,000 Mb or 35 times the size of the rice genome and 5 times the human genome. The relative lack of diversity in bread wheat has led to breeders and researchers crossing wheat varieties with relatives of wheat to increase genetic diversity and specifically to introduce beneficial traits such as disease resistance. Whilst a large number of SNPs have been identified in bread wheat, these have been identified in relatively few varieties and are not always relevant to the particular germplasm that a breeder is working in. In addition, many of the relatives that have been crossed into wheat have not had specific SNPs identified and represent a 'blind spot' to the breeders.This project aims to produce DNA sequence data for wheat genes for 280 wheat varieties, using a technology known as exome capture and 'next generation sequencing'. This is a complexity reduction process, which reduces the genome size and will enable us to produce sequence data for a large number of lines. The lines will be selected to contain key relatives that have been crossed into wheat. This data will enable us to identify the regions that we have been blind to, and to more accurately locate genes of interest so we can then breed for them using molecular markers. Ultimately, this will help us to develop varieties that have key traits for farmers, such as virus resistances, that will enable them to use less pesticides and to farm wheat more reliably.