HAPLOTYPE POLYMORPHISM IN POLYPLOID WHEATS AND THEIR DIPLOID ANCESTORS

点击翻译按钮获取中文摘要

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).