HAPLOTYPE POLYMORPHISM IN POLYPLOID WHEATS AND THEIR DIPLOID ANCESTORS

普通小麦是全球最重要的作物之一。因此，培育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。利用遗传标记进行有效选择是大多数小麦育种家优先考虑的问题。 遗传标记的例子包括可变（多态）基因或匿名DNA片段，可以很容易地进行基因分型。最普遍的多态性是DNA中的单核苷酸取代，单核苷酸多态性（SNP）。在NSF植物基因组研究计划资助的一个项目中，已经开发并绘制了超过7，000个小麦表达序列标签（EST）。EST是基因转录物的部分核苷酸序列（DBI-9975989; PI：Qualset）。虽然EST是基础遗传和进化研究的宝贵资源，但其在育种中的应用受到费力且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1，800个SNP，并将它们在小麦染色体上的定位和检测工具在公共数据库中提供。普通小麦是一种异源六倍体物种，起源于三个二倍体物种的种间杂交。利用本项目开发的部分资源，对小麦遗传变异的结构、小麦二倍体祖先对小麦遗传变异的贡献程度等进行初步研究，并考察小麦染色体上沿着的重组梯度对小麦染色体上遗传变异沿着分布的影响，以及重组对形成小麦等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.example.com）提供。www.gramene.org

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).