Establishing Chromosome Genomics In Wild Relatives Of Wheat To Support Gene Introgression

Breeding new varieties of wheat with improved yield and quality, and resistant to pests and adverse environmental conditions may be hampered by the lack of genomic loci underlying important traits in the wheat germplasm. A solution is to transfer particular loci from wild relatives either via interspecific hybridization or after cloning genes and their introduction by genetic transformation. Both approaches require knowledge of genome structure and development of markers linked with traits of interest. These tasks can be facilitated by applying chromosome genomics to narrow down the analysis to subgenomic regions. The reduction of genome complexity is achieved by flow cytometric chromosome sorting. However, due to similarity in relative DNA content, only some chromosomes can be discriminated and sorted in wild relatives. Other chromosomes and chromosome arms can be purified from alien chromosome substitution and alien telosome addition lines. To date we have verified a possibility to sort chromosomes from eight species of Aegilops and also from Hordeum chillense, Haynaldia villosa, Elymus tsukushiense and Thinopyrum elongatum. The potential of chromosome genomics was confirmed after shot-gun sequencing chromosome 1Ub of Ae. biuncialis and chromosomes 1U, 6U and 3U of Ae. umbellulata using the Illumina platform. The analysis of chromosome sequences provided first insights into the composition of Aegilops genomes, identified genic regions suitable for development of markers and established syntenic relationship between the Aegilops chromosomes and genomes of sequenced grasses. Our results suggest that chromosome genomics may provide the much needed knowledge and tools to support alien introgression breeding in wheat.