DArTseq-based analysis of genomic relationships among species of tribe Triticeae

Precise utilization of wild genetic resources to improve the resistance of their cultivated relatives to environmental growth limiting factors, such as salinity stress and diseases, requires a clear understanding of their genomic relationships. Although seriously criticized, analyzing these relationships in tribe Triticeae has largely been based on meiotic chromosome pairing in hybrids of wide crosses, a specialized and labourious strategy. In this study, DArTseq, an efficient genotyping-by-sequencing platform, was applied to analyze the genomes of 34 Triticeae species. We reconstructed the phylogenetic relationships among diploid and polyploid Aegilops and Triticum species, including hexaploid wheat. Tentatively, we have identified the diploid genomes that are likely to have been involved in the evolution of five polyploid species of Aegilops, which have remained unresolved for decades. Explanations which cast light on the progenitor of the A genomes and the complex genomic status of the B/G genomes of polyploid Triticum species in the Emmer and Timopheevi lineages of wheat have also been provided. This study has, therefore, demonstrated that DArTseq genotyping can be effectively applied to analyze the genomes of plants, especially where their genome sequence information are not available.

Genome polymorphism of the synthetic species xTrititrigia cziczinii Tsvel. inferred from AFLP analysis

×Trititrigia cziczinii Tsvel. is a synthetic species obtained as a result of hybridization of different wheat and wheat- grass species. ×T. cziczinii has unique characteristics, as it is a perennial species, with the ability to grow after mowing, high adaptability, resistance to diseases and pests, high protein and gluten content in the grain. All this makes it a promising new crop for agriculture. The new species is a good object for fundamental research in the field of genetics, phylogeny and evolution of cereals (Poaceae). However, there were practically no genetic studies of ×T. cziczinii. The aim of this work was to study the genetic diversity of 24 representatives of two ×T. cziczinii subspecies (ssp. Submitans and ssp. Perenne). To estimate interspecific differences, 17 samples of other tribe Triticeae species (Triticum aestivum, Triticum durum, Agropyron glaucum and Agropyron elon gatum, as well as samples of Triticum-Agropyron and TriticumElymus hybrids) were included in the analysis. For the study, AFLP method (Amplified Fragment Length Polymorphism) was chosen, which allowed us to reveal a sufficiently high polymorphism level of the studied samples. The two primer/enzyme combinations (EcoRI-ACT/MseI-CCC, EcoRI-ACT/MseI-CTA) allow ed the iden tification of 227 fragments, 224 of them were polymorphic (98.68 %), and the level of intraspecific polymorphism of 24 ×T. cziczinii samples was 68.15 %. The iden tified fragments of AFLP spectra, specific for the ×T. cziczinii representatives and the studied wheatgrass species, can be the basis for creating markers that will detect introgressions of genetic material of the genus Agropyron in the T. cziczinii ge nome. Our results indicate a greater genetic relatedness of ×T. cziczinii to T. aestivum than to representatives of the genus Agropyron. According to the cluster analysis, representatives of ×T. cziczinii and varieties of bread wheat were combined into a single subcluster, within which the samples of two species form separate groups. At the same time, the evaluation of the intraspecific genetic diversity of ×T. cziczinii showed  no reliable differentiation of representatives of the subspecies Submitans and Perenne, which is probably due to uncertain genetic nature of perenniality, the main feature that divides these subspecies. The study of the unique ×T. cziczinii collection allowed us to obtain the first data on the genetics of the species, while previous studies were focused mainly on phenotypic and economically valuable traits. AFLP analysis used in this study showed high efficiency when working with less studied species, and its results are promising and useful for understanding the genetic structure of the new species (×T. cziczinii Tsvel.).