Laying Foundations of Chromosome Genomics in Diploid Progenitors of Hexaploid Wheat

The A, B and D subgenomes of bread wheat originated from T. urartu (A^uA^u), a species similar to Aegilops speltoides (SS) and Ae. tauschii (DD), respectively. These species can provide new alleles for wheat breeding for improved yield and quality under unfavorable conditions. However, the introgression of desired traits from wild relatives to wheat is hampered by insufficient knowledge of their genomes and lack of molecular tools. The difficulties in analyzing the complex genomes of wheat and its relatives can be overcome by application of chromosome genomics. This approach greatly simplifies genome analysis by reducing sample complexity and has already been used in bread wheat to obtain chromosome shotgun sequences, develop markers and construct sequence-ready physical maps for chromosome arms. Chromosome genomics relies on the ability to dissect genomes to chromosomes via flow cytometric sorting. Here we report on flow cytometric chromosome sorting in wild wheats, T. urartu, Ae. speltoides and Ae. tauschii. Flow karyotypes of DAPI-stained chromosomes were characterized and content of chromosome peaks was determined. FISH analysis proved that chromosomes 5A^u, 2S and 5D could be sorted with 78 - 90% purity, while the remaining chromosomes could be sorted in groups of three. The isolation of individual chromosomes of wild progenitors provides an attractive opportunity to investigate the structure and evolution of the polyploid genome and deliver tools for wheat breeding. Financial support: PD83444, János Bolyai Scholarship, TÁMOP-4.2.2.A-11-1-KONV-2012-0008, Czech Science Foundation (P501/12/G090) and Czech Ministry of Education, Youth and Sports and the European Regional Development Fund (ED0007/01/01).