Abstract
BackgroundTriticum timopheevii (2n = 4x = 28; AtAtGG), is an important source for new genetic variation for wheat improvement with genes for potential disease resistance and salt tolerance. By generating a range of interspecific hybrid lines, T. timopheevii can contribute to wheat’s narrow gene-pool and be practically utilised in wheat breeding programmes. Previous studies that have generated such introgression lines between wheat and its wild relatives have been unable to use high-throughput methods to detect the presence of wild relative segments in such lines.ResultsA whole genome introgression approach, exploiting homoeologous recombination in the absence of the Ph1 locus, has resulted in the transfer of different chromosome segments from both the At and G genomes of T. timopheevii into wheat. These introgressions have been detected and characterised using single nucleotide polymorphism (SNP) markers present on a high-throughput Axiom® Genotyping Array. The analysis of these interspecific hybrid lines has resulted in the detection of 276 putative unique introgressions from T. timopheevii, thereby allowing the generation of a genetic map of T. timopheevii containing 1582 SNP markers, spread across 14 linkage groups representing each of the seven chromosomes of the At and G genomes of T. timopheevii. The genotyping of the hybrid lines was validated through fluorescence in situ hybridisation (FISH). Comparative analysis of the genetic map of T. timopheevii and the physical map of the hexaploid wheat genome showed that synteny between the two species is highly conserved at the macro-level and confirmed the presence of inter- and intra-genomic translocations within the At and G genomes of T. timopheevii that have been previously only detected through cytological techniques.ConclusionsIn this work, we report a set of SNP markers present on a high-throughput genotyping array, able to detect the presence of T. timopheevii in a hexaploid wheat background making it a potentially valuable tool for marker assisted selection (MAS) in wheat pre-breeding programs. These valuable resources of high-density molecular markers and wheat-T. timopheevii hybrid lines will greatly enhance the work being undertaken for wheat improvement through wild relative introgressions.
Highlights
Triticum timopheevii (2n = 4x = 28; AtAtGG), is an important source for new genetic variation for wheat improvement with genes for potential disease resistance and salt tolerance
Generation of wheat-T. timopheevii introgressions through homoeologous recombination in the absence of the Ph1 locus In order to generate wheat-T. timopheevii introgressions lines (Fig. 1) a total of 1947 crosses were made leading to the generation of 12,883 crossed seed and 7018 self-seed
150 interspecific F1 seeds were generated by crossing T. timopheevii with wheat having a mutation at the Ph1 locus resulting in homoeologous recombination between the chromosomes of the two species
Summary
Triticum timopheevii (2n = 4x = 28; AtAtGG), is an important source for new genetic variation for wheat improvement with genes for potential disease resistance and salt tolerance. A key factor in the plateauing of yields observed is the relatively small amount of genetic variation available in the gene pool of hexaploid wheat that can be used to develop new superior high yielding varieties adapted to the changing environment. Meiotic analysis by Feldman [14] of F1 hybrids between T. timopheevii and T. aestivum showed that the chromosomes of the B and G genomes paired to form bivalents, etc., only 30% of the time. In contrast the A and At genomes, appear to be more closely related as in the same study by Feldman [14] the chromosomes from these genomes paired 70% of the time
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