Comparative assessment of the copy number of satellite repeats in the genome of Triticeae species.

Satellite repeats are a significant component of the genome of Triticeae and play a crucial role in the speciation. They are a valuable tool for studying these processes. Pseudoroegneria species play a special role among grasses, as they are considered putative donors of the St-genome in many polyploid species. The aim of this study was to compare the copy number of satellite repeats in the genomes of Triticeae species. Quantitative real-time PCR was applied to determine the copy numbers of 22 newly discovered satellite repeats revealed in the whole-genome sequences of Pseudoroegneria species and one additional repeat previously identified in the genome of Aegilops crassa. The study focused on seven species of Pseudoroegneria, three species of Thinopyrum, Elymus pendulinus, Ae. tauschii, Secale cereale, and Triticum aestivum. Based on the copy number level and coefficients of variation, we identified three groups of repeats: those with low variability between species (medium-copy CL82), those with medium variability (low- and medium-copy CL67, CL3, CL185, CL119, CL192, CL89, CL115, CL95, CL168), and those with high coefficients of variation (CL190, CL184, CL300, CL128, CL207, CL69, CL220, CL101, CL262, CL186, CL134, CL251, CL244). CL69 exhibited a specific high copy number in all Pseudoroegneria species, while CL101 was found in both Pseudoroegneria and Th. junceum, CL244 in Th. bessarabicum, CL184 in P. cognata and S. cereale. CL95, CL128, CL168, CL186, CL207, and CL300 exhibited higher copy numbers in P. cognata compared to other species; CL3, CL95, CL115, CL119, CL190, CL220, CL207, and CL300 in P. kosaninii; CL89 in P. libanotica; CL134 in P. geniculata. Our assessment of the copy number of new satellite repeats in the St-genome and the analysis of their amplification specificity between species can contribute to the molecular-genetic and chromosome markers used for evolutionary, phylogenetic, and population studies of Triticeae species.

Pre-harvest sprouting resistance and haplotype variation of ThVp-1 gene in the collection of wheat-wheatgrass hybrids.

The germplasm collection of 87 wheat-wheatgrass hybrids developed in Tsitisin Main Botanical Garden (Russia, Moscow) was evaluated for resistance to pre-harvest sprouting (PHS) by spike sprouting (SS) and germination index (GI) assays as well as for spike and grain features. The PHS resistance variation and haplotype polymorphism of the wheatgrass ThVp-1 and wheat TaVp-1B genes orthologues of Vp-1 was revealed in the studied collection. Four haplotypes of ThVp-1 were revealed: ThVp-1a (41% of the entries), ThVp-1b (13%), ThVp-1c (29%), and ThVp-1d (15%). The association between the allelic state of ThVp-1 and PHS resistance in the wheat-wheatgrass hybrids was shown: haplotype ThVp-1d of the wheatgrass Vp-1 gene is significantly associated with reduced PHS in the wheat-wheatgrass hybrids (mean SS 0.33, mean GI 0.64). The resistant entries may be perspective as a source of PHS resistance in the development of commercial cultivars of perennial wheat.

[Analysis of allelic content of genes responsible for baking properties in allocytoplasmic wheat hybrids].

A collection comprised of allocytoplasmic hybrids of mild wheat (ACPH) was screened for the allelic state of genes responsible for baking properties (high-molecular glutenins, puroindolines, and Waxy). The possibility of the introgression of the Waxy gene of T. timopheevii into the mild wheat genome was demonstrated in several ACPH samples using the set of molecular markers. Allelic gene variants responsible for the baking properties were revealed for 22 ACPH samples, which make it possible to detect the most challenging samples for both molecular-genetic research and applied science.

[Identity of the Rht-11 and Rht-B1e reduced plant height genes].

The Rht (reduced plant height) genes provided a basis for the "green revolution", which led to a substantial increase in wheat productivity. More than 20 Rht genes are now known in wheat, Rht-B1 and Rht-11 being among the most important ones. Analysis of a segregating F2 population and molecular analysis of the common wheat cultivars carrying the Rht-11 gene showed that the Rht-11 and Rht-B1e genes are identical.

[Development of a sex-specific molecular marker for Japanese hop Humulus japonicus Siebold & Zucc].

Japanese hop (Humulus japonicus Siebold & Zucc.) is a dioecious plant and a suitable model for studying the XX/XY1Y2 system of sex chromosomes. To develop a sex-specific marker, 12 RAPD and 36 ISSR markers were analyzed on the basis of pools of male and female plants identified after flowering. We were the first to identify ISSR marker K-16, which manifested stable amplification of an approximately 300-bp fragment in male plants and the absence of amplification in female plants in the populations examined. Marker effectiveness was confirmed in several Japanese hop populations of different origin.

Molecular cytogenetic mapping of Humulus lupulus sex chromosomes.

Dioecy is relatively rare in plants and sex determination systems vary among such species. A good example of a plant with heteromorphic sex chromosomes is hop (Humulus lupulus). The genotypes carrying XX or XY chromosomes correspond to female and male plants, respectively. Until now no clear cytogenetic markers for the sex chromosomes of hop have been established. Here, for the first time the sex chromosomes of hop are clearly identified and characterized. The high copy sequence of hop (HSR1) has been cloned and localized on chromosomes by fluorescence in situ hybridization. The HSR1 repeat has shown subtelomeric location on autosomes with the same intensity of the signal. The signal has been present in the subtelomeric region of the long arm and in the near-centromeric region but absent in the telomeric region of the short arm of the X chromosome. At the same time the signal has been found in the telomeric region only of the long arm of the Y chromosome. This finding indicates that the sex chromosomes of hop have evolved from a pair of autosomes via ancient translocation or inversion. The observation of the meiotic configuration of the sex bivalents shows the location of a pseudoautosomal region on the long arms of X and Y chromosomes.

[Comparative molecular cytogenetic characterization of partial wheat-wheatgrass hybrids].

The chromosomal composition of the Zernokormovaya 169, Istra 1, Ostankinskaya, and Otrastayushchaya 38 cultivars of octoploid partial wheat-wheatgrass hybrids was studied using genomic in situ hybridization (GISH). Differentiation of wheatgrass chromosomes by the distribution of the GISH signal along the chromosome was revealed. The wheatgrass chromosomes of the hybrid cultivars studied in the work differed in the type of differentiation, centromeric index, and absolute size. The cytogenetic distinctions of these chromosomes revealed by us can be used in making crosses and in studying the transmission through gametes of additional wheatgrass chromosomes.

[The effect of selection for phenotypical characters on the chromosome constitution in spring triticale].

A set of spring triticale selection forms was studied with the use of microsatellite markers specific for D-genome chromosomes and genomic in situ hybridization. 2R/2D substitutions were found in six of twelve forms. Two lines displayed segregation for the substitution: plants with the substitution and without it, and plants heterozygous for the substitution were revealed. Segregation of the lines and the presence in them of telocentric chromosomes of wheat and rye in the monosomic state suggest that the process of formation is still in progress. The data obtained also demonstrate that triticale is under selection for the 2R/2D substitution as controlling the spectrum of adaptively and selectively valuable traits.

[Molecular cytogenetic characterization of spring triticale line 131/7 carrying a rye-wheat translocation].

The chromosomal composition of the spring triticale line 131/7 carrying a rye-wheat translocation was studied using GISH, C-banding, and SSR analysis. The complex analysis revealed the presence of a pair of 2D chromosomes and T2RS.2RL-2BL translocation in the genome of the hexaploid triticale line 131/7. The break point in the translocated chromosome is between the markers Xwmc592 and Xwmc441, loci 63.9 cM and 76.8 cM on the linkage map (Wheat, Consensus SSR, 2004 NA-SSR-2004-2B) and in the region C2BL2-0.36 on the physical map (Wheat, Physical, SSR). The analysis of the line enables its use in breeding programs and in genetic studies.