HAPLOTYPE POLYMORPHISM IN POLYPLOID WHEATS AND THEIR DIPLOID ANCESTORS

普通小麦（Triticum aestivum）是全球最重要的农作物之一。因此，开发抗病虫害和耐环境胁迫的高产小麦新品种是一个极其重要的目标。有效选择遗传标记的有效性是大多数小麦育种者优先考虑的问题。遗传标记的例子包括可变（多态）基因或可以很容易地进行基因分型的匿名DNA片段。最普遍的多态性是DNA中单核苷酸的替换，单核苷酸多态性（SNP）。许多检测DNA中snp的高通量策略已经开发出来，使snp成为许多育种情况下的选择标记。在美国国家科学基金会植物基因组研究计划资助的一个项目中，超过7000个小麦表达序列标签（est）已被开发和绘制。ESTs是基因转录物的部分核苷酸序列（DBI-9975989; PI: Qualset）。虽然无害环境技术是基础遗传和进化研究的宝贵资源，但其在育种方面的应用受到费力和昂贵的多态性检测技术的限制。在这个项目中，我们将使用这些est系统地搜索小麦基因中的SNPs。我们的目标是发现1800个snp，并将它们在小麦染色体中的位置和检测工具提供给可公开访问的数据库。普通小麦是由三个二倍体种间杂交而成的异源六倍体种。我们将利用本项目开发的部分资源，对小麦遗传变异的结构及其二倍体祖先对遗传变异的贡献程度进行初步研究。我们还将研究沿小麦染色体的重组梯度对遗传变异沿小麦染色体分布的影响，以及重组对形成小麦和其他物种遗传变异的影响。项目数据和材料将通过Gramene数据库（http://www.gramene.org）提供。

Common wheat, Triticum aestivum, is globally one of the most important crops. The development of new high-yielding wheat varieties resistant to pests and diseases and tolerant of environmental stresses is therefore an exceedingly important objective. The availability of genetic markers for efficient selection is high on the priority list of most wheat breeders. Examples of genetic markers include variable (polymorphic) genes or anonymous DNA segments that can be easily genotyped. The most widespread polymorphisms are substitutions of single-nucleotides in DNA, single nucleotide polymorphism (SNP). Numerous high-throughput strategies for the detection of SNPs in DNA have been developed making SNPs the markers of choice in many breeding situations.In a project funded by the NSF Plant Genome Research program, over 7,000 wheat expressed sequence tags (ESTs) have been developed and mapped. ESTs are partial nucleotide sequences of gene transcripts (DBI-9975989; PI: Qualset). Although ESTs are a valuable resource for basic genetic and evolutionary research, their utility for breeding is limited by laborious and expensive polymorphism detection techniques. In this project, we will use these ESTs in a systematic search for SNPs in wheat genes. Our target is to discover 1,800 SNPs and make their location in wheat chromosomes and tools for their detection available in publicly accessible databases.Common wheat is an allohexapolyploid species that originated by interspecific hybridization of three diploid species. We will employ some of the resources developed in this project for preliminary studies on the structure of genetic variation in wheat and the extent to which wheat diploid ancestors contributed to it. We will also examine the influence of recombination gradients along wheat chromosomes on the distribution of genetic variation along wheat chromosomes and the effects of recombination on shaping genetic variation in wheat and other species. Project data and materials will be made available through the Gramene database (http://www.gramene.org).