Multicolour fluorescence in situ hybridisation (MCFISH), Simple Sequence Repeat markers (SSR) and Diversity Arrays Technology (DArT) markers were employed in this study to analyse six generations of interspecific wheat crosses between a Crown Rot (CR) resistant hexaploid wheat (Triticum aestivum L. var.2-49) and three tetraploid durum wheat lines (T. turgidum L. spp. durum (Desf.) var. M= 961111 (Bellaroi); N= 950329; O=971179), over the years 2005-2009. In the F2 progeny from a 2-49/Bellaroi cross, 82 out of 83 F2 plants investigated with DArT analysis carried some D genome material, principally as entire chromosomes, while 40 plants included at least one complete copy of all seven D genome chromosomes. Twelve plants containing partial D chromosomes were identified. MCFISH analysis of 26 additional F2 plants of the same cross showed that all 26 plants contained varying amounts of D genome material of which three carried single A-D translocations. In addition, two telocentric D genome chromosomes were detected. The D genome content of each line and the breakpoint positions of the three A-D translocations were confirmed with DArT marker analysis. Overall results indicate a random recombination of A and B genome loci from the hexaploid female parent and the tetraploid male parent in this F2 population and a significant retention of the maternal D genome material.
SSR markers linked to CR seedling resistance in 2-49 in previous studies were useful for the prediction of CR resistance in the crosses. DArT analysis of 191 F7 plants revealed significant QTL for CR on chromosomes 1A and 4B. D chromatin was not responsible for CR resistance, as it was progressively eliminated throughout successive generations.
This study illustrates that the combined application of SSR markers, MCFISH and DArT techniques provides a powerful approach for the analysis of crosses between cereal genotypes of different ploidy
