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，也是这些消费者饮食中仅次于大米的第二大卡路里来源。它是英国种植最广泛的可耕地作物，每年的种植面积约为180万公顷。英国的育种家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：在1948年至2006年期间，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，小麦产量的增长并没有跟上需求的增长。此外，小麦生产力受到病害、对优质农业用地的竞争、资源限制和不利的环境条件的威胁，这些都大大降低了最佳产量。据估计，欧洲的生产率需要翻一番才能跟上需求并保持稳定的价格。为了帮助植物育种家改良小麦品种，他们利用了遗传变异，特别是单核苷酸多态性（SNPs），这些变异与抗病、对特定环境的适应、面包制作质量特征和产量组成等已知性状有关。育种者使用分子标记来追踪相关的snp，作为这些有益性状的代理。这样做的好处是可以更快、更便宜地筛选数千个品系，而且在某些情况下，比在田间种植以常规方式评估品系更准确。小麦是从两个自然发生的独立杂交事件进化而来的，每个杂交事件都产生了一个遗传瓶颈。首先，两种野草杂交形成面食小麦的亲缘种。随后，第三种野草杂交产生面包小麦。因此，总基因组大小约为16000 Mb，是水稻基因组大小的35倍，是人类基因组大小的5倍。面包小麦多样性的相对缺乏导致育种者和研究人员将小麦品种与小麦的亲缘品种杂交，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snp，并且并不总是与育种者正在研究的特定种质有关。此外，许多与小麦杂交的亲缘关系还没有鉴定出特定的snp，这对育种者来说是一个“盲点”。该项目旨在利用一种被称为外显子组捕获和“下一代测序”的技术，为280个小麦品种的小麦基因提供DNA序列数据。这是一个减少复杂性的过程，它减少了基因组的大小，使我们能够为大量的系产生序列数据。将选择包含已杂交成小麦的关键亲缘关系的品系。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，然后我们可以使用分子标记为它们繁殖。最终，这将帮助我们开发出对农民来说具有关键特性的品种，比如病毒抗性，这将使他们使用更少的农药，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.