Breeding of agricultural crops adapted to climate change and resistant to diseases and pests is hindered by a limited gene pool because of domestication and thousands of years of human selection. One way to increase genetic variation is chromosome-mediated gene transfer from wild relatives by cross hybridization. In the case of wheat (Triticum aestivum), the species of genus Aegilops are a particularly attractive source of new genes and alleles. However, during the evolution of the Aegilops and Triticum genera, diversification of the D-genome lineage resulted in the formation of diploid C, M, and U genomes of Aegilops. The extent of structural genome alterations, which accompanied their evolution and speciation, and the shortage of molecular tools to detect Aegilops chromatin hamper gene transfer into wheat. To investigate the chromosome structure and help develop molecular markers with a known physical position that could improve the efficiency of the selection of desired introgressions, we developed single-gene fluorescence in situ hybridization (FISH) maps for M- and U-genome progenitors, Aegilops comosa and Aegilops umbellulata, respectively. Forty-three ortholog genes were located on 47 loci in Ae. comosa and on 52 loci in Ae. umbellulata using wheat cDNA probes. The results obtained showed that M-genome chromosomes preserved collinearity with those of wheat, excluding 2 and 6M containing an intrachromosomal rearrangement and paracentric inversion of 6ML, respectively. While Ae. umbellulata chromosomes 1, 3, and 5U maintained collinearity with wheat, structural reorganizations in 2, 4, 6, and 7U suggested a similarity with the C genome of Aegilops markgrafii. To develop molecular markers with exact physical positions on chromosomes of Aegilops, the single-gene FISH data were validated in silico using DNA sequence assemblies from flow-sorted M- and U-genome chromosomes. The sequence similarity search of cDNA sequences confirmed 44 out of the 47 single-gene loci in Ae. comosa and 40 of the 52 map positions in Ae. umbellulata. Polymorphic regions, thus, identified enabled the development of molecular markers, which were PCR validated using wheat-Aegilops disomic chromosome addition lines. The single-gene FISH-based approach allowed the development of PCR markers specific for cytogenetically mapped positions on Aegilops chromosomes, substituting as yet unavailable segregating map. The new knowledge and resources will support the efforts for the introgression of Aegilops genes into wheat and their cloning.

Wheat-rye T1BL.1RS translocation is widespread worldwide as the genes on 1RS arm have positive effect on stress resistance, grain yield and adaptation ability of wheat. Nowadays, the T1BL.1RS wheat cultivars have become susceptible to rust diseases because of the monophyletic ('Petkus') origin of 1RS. Here we report and discuss the production and detailed investigation of a new T1BL.1RS translocation line carrying 1RS with widened genetic base originating from Secale cereanum. Line '179' exhibited improved spike morphology traits, resistance against stripe rust and leaf rust, as well as higher tillering capacity, fertility and dietary fiber (arabynoxylan) content than the parental wheat genotype. Comparative analyses based on molecular cytogenetic methods and molecular (SSR and DArTseq) makers indicate that the 1RS arm of line '179' is a recombinant of S. cereale and S. strictum homologues, and approximately 16% of its loci were different from that of 'Petkus' origin. 162 (69.5%) 1RS-specific markers were associated with genes, including 10 markers with putative disease resistance functions and LRR domains found on the subtelomeric or pericentromeric regions of 1RS. Line '179' will facilitate the map-based cloning of the resistance genes, and it can contribute to healthy eating and a more cost-efficient wheat production. Interspecific hybridization is one of the most promising way to improve the genetic diversity of bread wheat 1. The most widely known wheat-alien introgression has been the spontaneous translocation T1BL.1RS that is traced back to the cross of wheat 'Criewener 104' × rye 'Petkus Roggen' made in Germany between 1920 and 1930 2. Its effect on morphology and baking quality of bread wheat has been investigated in numerous studies. The positive effect of this translocation on grain yield of hexaploid wheat 3,4 and durum wheat 5,6 is commonly accepted, though in some cases no such effect was shown 7,8. Association between the presence of 1RS and increase in root biomass, water use efficiency as well as harvest index was also found in glasshouse and field experiments 9,10. 1RS arm also contains genes (Pm8, Lr26, Sr31 and Yr9) providing resistance against powdery mildew (Erysiphe graminis f. sp. tritici), leaf rust (Puccinia triticina), stem rust (Puccinia graminis f. sp. tritici), and stripe or yellow rust (Puccinia striiformis f. sp. tritici), respectively 11,12 , a reason that led to the widespread utilization of the T1BL.1RS translocation in wheat improvement. However, the resistance genes Lr26, Yr9 and Pm8 are no longer effective against new virulent biotypes of the pathogens in Europe 13. Virulence to the Sr31 resistance gene has also been reported from Uganda 14 , and from Kenya, Ethiopia, Sudan, and Iran 15. Spread of the Sr31-virulent pathotype in countries where wheats carrying the T1BL.1RS chromosome are cultivated can cause serious problems for agriculture as the genetic vulnerability of T1BL.1RS cultivars is the consequence of the lack of allelic variation on the 'Petkus'-derived 1RS arm 4. ...

Understanding the genetic diversity of Aegilops biuncialis, a valuable source of agronomical useful genes, may significantly facilitate the introgression breeding of wheat. The genetic diversity and population structure of 86 Ae. biuncialis genotypes were investigated by 32700 DArT markers with the simultaneous application of three statistical methods— neighbor-joining clustering, Principal Coordinate Analysis, and the Bayesian approach to classification. The collection of Ae. biuncialis accessions was divided into five groups that correlated well with their eco-geographic habitat: A (North Africa), B (mainly from Balkans), C (Kosovo and Near East), D (Turkey, Crimea, and Peloponnese), and E (Azerbaijan and the Levant region). The diversity between the Ae. biuncialis accessions for a phenological trait (heading time), which is of decisive importance in the adaptation of plants to different eco-geographical environments, was studied over 3 years. A comparison of the intraspecific variation in the heading time trait by means of analysis of variance and principal component analysis revealed four phenotypic categories showing association with the genetic structure and geographic distribution, except for minor differences. The detailed exploration of genetic and phenologic divergence provides an insight into the adaptation capacity of Ae. biuncialis, identifying promising genotypes that could be utilized for wheat improvement.