Identification of Novel Loci Precisely Modulating Pre-Harvest Sprouting Resistance and Red Color Components of the Seed Coat in T. aestivum L

The association between pre-harvest sprouting (PHS) and seed coat color has long been recognized. Red-grained wheats generally exhibit greater PHS resistance compared to white-grained wheat, although variability in PHS resistance exists within red-grained varieties. Here, we conducted a genome-wide association study on a panel consisting of red-grained wheat varieties, aimed at uncovering genes that modulate PHS resistance and red color components of seed coat using digital image processing. Twelve loci associated with PHS traits were identified, nine of which were described for the first time. Genetic loci marked by SNPs AX-95172164 (chromosome 1B) and AX-158544327 (chromosome 7D) explained approximately 25% of germination index variance, highlighting their value for breeding PHS-resistant varieties. The most promising candidate gene for PHS resistance was TraesCS6B02G147900, encoding a protein involved in aleurone layer morphogenesis. Twenty-six SNPs were significantly associated with grain color, independently of the known Tamyb10 gene. Most of them were related to multiple color characteristics. Prioritization of genes within the revealed loci identified TraesCS1D03G0758600 and TraesCS7B03G1296800, involved in the regulation of pigment biosynthesis and in controlling pigment accumulation. In conclusion, our study identifies new loci associated with grain color and germination index, providing insights into the genetic mechanisms underlying these traits.

GBS-DP: a bioinformatics pipeline for processing data coming from genotyping by sequencing

The development of next-generation sequencing technologies has provided new opportunities for genotyping various organisms, including plants. Genotyping by sequencing (GBS) is used to identify genetic variability more rapidly, and is more cost-effective than whole-genome sequencing. GBS has demonstrated its reliability and flexibility for a number of plant species and populations. It has been applied to genetic mapping, molecular marker discovery, genomic selection, genetic diversity studies, variety identification, conservation biology and evolutionary studies. However, reduction in sequencing time and cost has led to the need to develop efficient bioinformatics analyses for an ever-expanding amount of sequenced data. Bioinformatics pipelines for GBS data analysis serve the purpose. Due to the similarity of data processing steps, existing pipelines are mainly characterised by a combination of software packages specifically selected either to process data for certain organisms or to process data from any organisms. However, despite the usage of efficient software packages, these pipelines have some disadvantages. For example, there is a lack of process automation (in some pipelines, each step must be started manually), which significantly reduces the performance of the analysis. In the majority of pipelines, there is no possibility of automatic installation of all necessary software packages; for most of them, it is also impossible to switch off unnecessary or completed steps. In the present work, we have developed a GBS-DP bioinformatics pipeline for GBS data analysis. The pipeline can be applied for various species. The pipeline is implemented using the Snakemake workflow engine. This implementation allows fully automating the process of calculation and installation of the necessary software packages. Our pipeline is able to perform analysis of large datasets (more than 400 samples).

Identification of genetic loci for early maturity in spring bread wheat using the association analysis and gene dissection

Background

Early maturity in spring bread wheat is highly desirable in the regions where it enables the plants to evade high temperatures and plant pathogens at the end of the growing season.

Methods

To reveal the genetic loci responsible for the maturity time association analysis was carried out based on phenotyping for an 11-year period and high-throughput SNP genotyping of a panel of the varieties contrasting for this trait. The expression of candidate genes was verified using qPCR. The association between the SNP markers and the trait was validated using the biparental F2:3 population.

Results

Our data showed that under long-day conditions, the period from seedling to maturity is mostly influenced by the time from heading to maturity, rather than the heading time. The QTLs associated with the trait were located on 2A, 3B, 4A, 5B, 7A and 7B chromosomes with the 7BL locus being the most significant and promising for its SNPs accelerated the maturity time by about 9 days. Gene dissection in this locus detected a number of candidates, the best being TraesCS7B02G391800 (bZIP9) and TraesCS7B02G412200 (photosystem II reaction center). The two genes are predominantly expressed in the flag leaf while flowering. The effect of the SNPs was verified in F2:3 population and confirmed the association of the 4A, 5B and 7BL loci with the maturity time.

Population Structure and Genetic Diversity of the 175 Soybean Breeding Lines and Varieties Cultivated in West Siberia and Other Regions of Russia

Soybean is a leguminous plant cultivated in many countries and is considered important in the food industry due to the high levels of oil and protein content in the beans. The high demand for soybeans and its products in the industry requires the expansion of cultivation areas. Despite climatic restrictions, West Siberia is gradually expanding its area of soybean cultivation. In this study, we present the first analysis of the population structure and genetic diversity of the 175 soybean Glycine max breeding lines and varieties cultivated in West Siberia (103 accessions) and other regions of Russia (72 accessions), and we compare them with the cultivated soybean varieties from other geographical locations. Principal component analysis revealed several genetic clusters with different levels of genetic heterogeneity. Studied accessions are genetically similar to varieties from China, Japan, and the USA and are genetically distant to varieties from South Korea. Admixture analysis revealed four ancestry groups based on genetic ancestry and geographical origin, which are consistent with the regions of cultivation and origin of accessions and correspond to the principal component analysis result. Population statistics, including nucleotide diversity, Tajima's D, and linkage disequilibrium, are comparatively similar to those observed for studied accessions of a different origin. This study provides essential population and genetic information about the unique collection of breeding lines and varieties cultivated in West Siberia and other Russian regions to foster further evolutionary, genome-wide associations and functional breeding studies.

Novel Genetic Loci from Triticum timopheevii Associated with Gluten Content Revealed by GWAS in Wheat Breeding Lines

The content and quality of gluten in wheat grain is a distinctive characteristic that determines the final properties of wheat flour. In this study, a genome-wide association study (GWAS) was performed on a wheat panel consisting of bread wheat varieties and the introgression lines (ILs) obtained via hybridization with tetraploid wheat relatives. A total of 17 stable quantitative trait nucleotides (QTNs) located on chromosomes 1D, 2A, 2B, 3D, 5A, 6A, 7B, and 7D that explained up to 21% of the phenotypic variation were identified. Among them, the QTLs on chromosomes 2A and 7B were found to contain three and six linked SNP markers, respectively. Comparative analysis of wheat genotypes according to the composition of haplotypes for the three closely linked SNPs of chromosome 2A indicated that haplotype TT/AA/GG was characteristic of ten ILs containing introgressions from T. timopheevii. The gluten content in the plants with TT/AA/GG haplotype was significantly higher than in the varieties with haplotype GG/GG/AA. Having compared the newly obtained data with the previously reported quantitative trait loci (QTLs) we inferred that the locus on chromosome 2A inherited from T. timopheevii is potentially novel. The introgression lines containing the new locus can be used as sources of genetic factors to improve the quality traits of bread wheat.

Multivariate Genome-Wide Association Study of Concentrations of Seven Elements in Seeds Reveals Four New Loci in Russian Wheat Lines

Wheat is a cereal grain that plays an important role in the world's food industry. The identification of the loci that change the concentration of elements in wheat seeds is an important challenge nowadays especially for genomic selection and breeding of novel varieties. In this study, we performed a multivariate genome-wide association study (GWAS) of the seven traits-concentrations of Zn, Mg, Mn, Ca, Cu, Fe, and K in grain-of the Russian collection of common wheat Triticum aestivum (N = 149 measured in two years in two different fields). We replicated one known locus associated with the concentration of Zn (IAAV1375). We identified four novel loci-BS00022069_51 (associated with concentrations of Ca and K), RFL_Contig6053_3082 (associated with concentrations of Fe and Mn), Kukri_rep_c70864_329 (associated with concentrations of all elements), and IAAV8416 (associated with concentrations of Fe and Mn)-three of them were located near the genes TraesCS6A02G375400, TraesCS7A02G094800, and TraesCS5B02G325400. Our result adds novel information on the loci involved in wheat grain element contents and may be further used in genomic selection.

[Genotype-Specific Features of Cold-Induced Sweetening Process Regulation in Potato Varieties Nikulinsky, Symfonia, and Nevsky]

In this study, we performed expression analysis of genes associated with cold-induced sweetening in potato tubers: vacuolar invertase (Pain-1), sucrose synthase (SUS4), and invertase inhibitor (InvInh2). Potato varieties Nikulinsky, Symfonia, and Nevsky were used. All three varieties were found to accumulate sugars at low temperatures; the maximum accumulation of reducing sugars was observed at 4°C. It was found that the expression pattern of genes associated with cold-induced sweetening differs depending on the variety and storage duration. The increased expression of vacuolar invertase and its inhibitor is more pronounced at the beginning of storage period, whereas the increased expression of sucrose synthase is more pronounced after 3 months of storage. At early storage periods, high expression of invertase and low expression of inhibitor is observed in the Dutch variety Symfonia, and vice versa in the Russian varieties Nikulinsky and Nevsky. The involvement of the studied genes in the process of cold-induced sweetening is discussed.

SSR Variability of Stem Rust Pathogen on Spring Bread Wheat in Russia

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, which used to be a harmful disease of winter wheat in the southern part of Russia, has been largely affecting the yield of spring bread wheat in the territories of the temperate climate zone since 2009. In total, 222 P. graminis f. sp. tritici isolates were obtained from samples of susceptible cultivars of spring bread wheat in Central and Volga regions and Omsk and Novosibirsk provinces in 2019. Genotyping of the isolates was carried out at 16 simple-sequence repeat (SSR) loci. Number of alleles, proportion of heterozygotes, and deviation from Hardy-Weinberg equilibrium were determined at each SSR locus. Based on genetic variability of SSR genotypes, it was shown that the P. graminis f. sp. tritici population is subdivided into two large clusters in the territory of the Russian temperate climate zone: the "European" population (the Central region) and the "Asian" one (the Volga region and two main wheat provinces of Western Siberia). Both of the P. graminis f. sp. tritici populations are characterized by a mixed mode of reproduction (sexual and clonal) but different sources of inoculum seem to shape a genotype structure within them. A group of P. graminis f. sp. tritici genotypes with high variability, the inbreeding coefficient closed to zero, and low observed heterozygosity was revealed among samples from Omsk. Moreover, two singular SSR genotypes identified among the Asian samples of P. graminis f. sp. tritici isolates should attract special attention in the monitoring of stem rust in order to disclose unexpected rapid changes of the pathogen in the corresponding regions and to prevent disease outbreak.

[Efficacy of Mexidol in the correction of postcovid syndrome in patients with chronic cerebrovascular diseases]

OBJECTIVE

To evaluate the effectiveness of sequential therapy with Mexidol and Mexidol FORTE 250 in the correction of postcovoid syndrome (PKS) in patients with chronic cerebrovascular diseases (CVD).

MATERIAL AND METHODS

The analysis of the results of examination and treatment of 110 patients with CVD who underwent COVID-19 was carried out. Patients of the main group (OH, n=55) received Mexidol (5 ml IV drip for 14 days, followed by the transition to the tablet form of Mexidol FORTE 250 1 table 3 times/day for 2 months); 55 patients of the comparison group (GS) did not receive antioxidants. All patients included in the study were conducted MRI examination and extensive neuropsychological testing.

RESULTS

There was a significant improvement in the state of cognitive functions, regression of symptoms of asthenia, improvement of night sleep in patients with OG. The differences were statistically significant both in comparison with the baseline level and the HS.

CONCLUSION

The administration of the drug does not require age-related dose adjustment and is well combined with basic therapy. The recommended regimen for the use of Mexidol: 14 days of 5 ml i/v or i/m, then taking the drug Mexidol FORTE 250 at a dose of 1 table 3 times/day for 2 months.

Infections, Pandemics, and Sleep Disorders

Studies of the neurological symptoms and signs associated with the acute and late phases of infectious diseases are important in pandemic conditions. The novel coronavirus infection (COVID-19) pandemic has increased the number of patients with sleeplessness, this being an adverse prognostic factor for infections. This review addresses the factors and mechanisms of sleep impairments and their relationship with inflammation and immune system dysfunction in infectious diseases. In particular, impairments to the functioning of the melatoninergic system are discussed as the cause of sleeplessness during pandemics. The relevance of developing measures for rehabilitating patients, particularly use of Sonnovan to restore normal sleep, which plays a fundamental role in supporting people's mental and physical health, is emphasized.

Functional characterization of genes with daily expression patterns in common wheat

Our findings suggest most wheat biological processes are under the control of the daily expressed genes. Plant circadian rhythms represent daily changes in the activity of various processes, which are based on changes in the levels of gene expression and protein synthesis. In wheat, some key components of plant circadian clock have been identified, but there is little data on the daily expression and interactions of these genes. To study the common wheat daily transcriptome, RNA sequencing was performed. Using these data, genes expressed in daily pattern and the metabolic pathways controlled by them were identified: responses to stimuli and nutrients, transport, photoperiodism, photomorphogenesis, synthesis and degradation of different metabolites, and regulation of the processes of RNA synthesis. It was shown that a significant part of the transcriptome can vary greatly daily. Five expression patterns were identified. They were characterized by peaks at different time points and described the genes underlying these patterns. The analysis of the enrichment of gene ontology terms with various patterns allowed us to describe the main metabolic pathways in each group. Wheat homologs of the genes related to circadian clock in Arabidopsis were identified. Most of them were represented by three homoeologous genes expressed uniformly. Comparison of their expression patterns demonstrated a shift in the expression peaks for some core and accessory genes; the majority of wheat circadian genes were expressed in accordance with Arabidopsis homologs. This may indicate a similar functional role of these genes in wheat.

Identification of QTLs for Grain Protein Content in Russian Spring Wheat Varieties

Most modern breeding programs aim to develop wheat (T. aestivum L.) varieties with a high grain protein content (GPC) due to its greater milling and cooking quality, and improved grain price. Here, we used a genome-wide association study (GWAS) to map single nucleotide polymorphisms (SNPs) associated with GPC in 93 spring bread wheat varieties developed by eight Russian Breeding Centers. The varieties were evaluated for GPC, grain weight per spike (GWS), and thousand-kernel weight (TKW) at six environments, and genotyped with 9351 polymorphic SNPs and two SNPs associated with the NAM-A1 gene. GPC varied from 9.8 to 20.0%, depending on the genotype and environment. Nearly 52% of the genotypes had a GPC > 14.5%, which is the threshold value for entry into high-class wheat varieties. Broad-sense heritability for GPC was moderate (0.42), which is due to the significant effect of environment and genotype × environment interactions. GWAS performed on mean GPC evaluated across six environments identified eleven significant marker-trait associations, of which nine were physically mapped on chromosome 6A. Screening of wheat varieties for allelic variants of the NAM-A1 gene indicated that 60% of the varieties contained the NAM-A1c allele, followed by 33% for NAM-A1d, and 5% for NAM-A1a alleles. Varieties with the NAM-A1d allele showed significantly (p < 0.01) smaller GPC than those with NAM-A1c and NAM-A1a. However, no significant differences between NAM-A1 alleles were observed for both GWS and TKW.

Development of a marker panel for genotyping of domestic soybean cultivars for genes controlling the duration of vegetation and response to photoperiod

Soybean, Glycine max L., is one of the most important agricultural crops grown in a wide range of latitude. In this regard, in soybean breeding, it is necessary to pay attention to the set of genes that control the transition to the f lowering stage, which will make it possible to adapt genotypes to local growing conditions as accurately as possible. The possibilities of soybean breeding for this trait have now signif icantly expanded due to identif ication of the main genes (E1–E4, GmFT2a, GmFT5a) that control the processes of f lowering and maturation in soybean, depending on the day length. The aim of this work was to develop a panel of markers for these genes, which could be used for a rapid and eff icient genotyping of domestic soybean cultivars and selection of plant material based on sensitivity to photoperiod and the duration of vegetation. Combinations of 10 primers, both previously developed and our own, were tested to identify different alleles of the E1–E4, GmFT2a, and GmFT5a genes using 10 soybean cultivars from different maturity groups. As a result, 5 combinations of dominant and recessive alleles for the E1–E4 genes were identif ied: (1) e1-nl(e1-as)/ e2-ns/e3-tr(e3-fs)/e4; (2) e1-as/e2-ns/e3-tr/E4; (3) e1-as/e2-ns/E3-Ha/e4; (4) E1/e2-ns/e3-tr/E4; (5) e1-nl/e2-ns/E3-Ha/E4. The studied cultivars contained the most common alleles of the GmFT2a and GmFT5a genes, with the exception of the ‘Cassidi’ cultivar having a rare dominant allele GmFT5a-H4. The degree of earliness of cultivars positively correlated with the number of recessive genes E1–E4, which is consistent with the data of foreign authors on different sets of cultivars from Japan and North China. Thus, the developed panel of markers can be successfully used in the selection of soybean for earliness and sensitivity to photoperiod.

Genetic Features of Triticale–Wheat Hybrids with Vaviloid-Type Spike Branching

Vaviloid spike branching, also called sham ramification, is a typical trait of Triticum vavilovii Jakubz. and is characterized by a lengthening of the spikelet axis. In this article, we present the results of a study of three triticale–wheat hybrid lines with differences in terms of the manifestation of the vaviloid spike branching. Lines were obtained by crossing triticale with hexaploid wheat, T. aestivum var. velutinum. The parental triticale is a hybrid of synthetic wheat (T. durum × Ae. tauschii var. meyrei) with rye, S. cereale ssp. segetale. Line 857 has a karyotype corresponding to hexaploid wheat and has a spike morphology closest to normal, whereas Lines 808/1 and 844/4 are characterized by the greatest manifestation of vaviloid spike branching. In Lines 808/1 and 844/4, we found the substitution 2RL(2DL). The karyotypes of the latter lines differ in that a pair of telocentric chromosomes 2DS is detected in Line 808/1, and these telocentrics are fused into one unpaired chromosome in Line 844/4. Using molecular genetic analysis, we found a deletion of the wheat domestication gene Q located on 5AL in the three studied hybrid lines. The deletion is local since an analysis of the adjacent gene B1 showed the presence of this gene. We assume that the manifestation of vaviloid spike branching in two lines (808/1 and 844/4) is associated with a disturbance in the joint action of genes Q and AP2L2-2D, which is another important gene that determines spike morphology and is located on 2DL.

The gene Sr38 for bread wheat breeding in Western Siberia

Present-day wheat breeding for immunity exploits extensively closely related species from the family Triticeae as gene donors. The 2NS/2AS translocation has been introduced into the genome of the cultivated cereal Triticum aestivum from the wild relative T. ventricosum. It contains the Lr37, Yr17, and Sr38 genes, which support seedling resistance to the pathogens Puccinia triticina Eriks., P. striiformis West. f. sp. tritici, and P. graminis Pers. f. sp. tritici Eriks. & E. Henn, which cause brown, yellow, and stem rust of wheat, respectively. This translocation is present in the varieties Trident, Madsen, and Rendezvous grown worldwide and in the Russian varieties Morozko, Svarog, Graf, Marquis, and Homer bred in southern regions. However, the Sr38 gene has not yet been introduced into commercial varieties in West Siberia; thus, it remains of practical importance for breeding in areas where populations of P. graminis f. sp. tritici are represented by avirulent clones. The main goal of this work was to analyze the frequency of clones (a)virulent to the Sr38 gene in an extended West Siberian collection of stem rust agent isolates. In 2019–2020, 139 single pustule isolates of P. graminis f. sp. tritici were obtained on seedlings of the standard susceptible cultivar Khakasskaya in an environmentally controlled laboratory (Institute of Cytology and Genetics SB RAS) from samples of urediniospores collected on commercial and experimental bread wheat f ields in the Novosibirsk, Omsk, Altai, and Krasnoyarsk regions. By inoculating test wheat genotypes carrying Sr38 (VPM1 and Trident), variations in the purity of (a)virulent clones were detected in geographical samples of P. graminis f. sp. tritici. In general, clones avirulent to Sr38 constitute 60 % of the West Siberian fungus population, whereas not a single virulent isolate was detected in the Krasnoyarsk collection. The Russian breeding material was screened for sources of the stem rust resistance gene by using molecular markers specif ic to the 2NS/2AS translocation. A collection of hybrid lines and varieties of bread spring wheat adapted to West Siberia (Omsk SAU) was analyzed to identify accessions promising for the region. The presence of the gene was postulated by genotyping with specif ic primers (VENTRIUP-LN2) and phytopathological tests with avirulent clones of the fungus. Dominant Sr38 alleles were identif ied in Lutescens 12-18, Lutescens 81-17, Lutescens 66-16, Erythrospermum 79/07, 9-31, and 8-26. On the grounds of the composition of the West Siberian P. graminis f. sp. tritici population, the Sr38 gene can be considered a candidate for pyramiding genotypes promising for the Novosibirsk, Altai, and Krasnoyarsk regions

Crop pangenomes

Progress in genome sequencing, assembly and analysis allows for a deeper study of agricultural plants' chromosome structures, gene identification and annotation. The published genomes of agricultural plants proved to be a valuable tool for studing gene functions and for marker-assisted and genomic selection. However, large structural genome changes, including gene copy number variations (CNVs) and gene presence/absence variations (PAVs), prevail in crops. These genomic variations play an important role in the functional set of genes and the gene composition in individuals of the same species and provide the genetic determination of the agronomically important crops properties. A high degree of genomic variation observed indicates that single reference genomes do not represent the diversity within a species, leading to the pangenome concept. The pangenome represents information about all genes in a taxon: those that are common to all taxon members and those that are variable and are partially or completely specific for particular individuals. Pangenome sequencing and analysis technologies provide a large-scale study of genomic variation and resources for an evolutionary research, functional genomics and crop breeding. This review provides an analysis of agricultural plants' pangenome studies. Pangenome structural features, methods and programs for bioinformatic analysis of pangenomic data are described.

[Infections, pandemics and sleep disorders]

The study of neurological symptoms and signs connected with acute and long-term periods of infectious diseases is relevant during pandemics. The COVID-19 pandemic has increased the number of patients suffering from insomnia. Sleep disturbance is an unfavorable prognostic factor for infections. Risk factors and mechanisms of sleep disturbance, their relationship with inflammation and dysfunction of the immune system in infectious diseases are presented. In particular, dysfunction of the melatonergic system as the cause of insomnia during pandemics is considered. The authors highlight the relevance of measures aimed at the rehabilitation of patients, in particular, the use of sonnovan to restore normal sleep, which is important for a person's mental and physical health.

Genome-wide association study of leaf rust resistance in Russian spring wheat varieties

BACKGROUND

Leaf rust (Puccinia triticina Eriks.) is one of the most dangerous diseases of common wheat worldwide. Three approaches: genome-wide association study (GWAS), marker-assisted selection (MAS) and phytopathological evaluation in field, were used for assessment of the genetic diversity of Russian spring wheat varieties on leaf rust resistance loci and for identification of associated molecular markers.

RESULTS

The collection, consisting of 100 Russian varieties of spring wheat, was evaluated over three seasons for resistance to the native population of leaf rust specific to the West Siberian region of Russia. The results indicated that most cultivars showed high susceptibility to P. triticina, with severity ratings (SR) of 60S-90S, however some cultivars showed a high level of leaf rust resistance (SR < 20MR-R). Based on the results of genome-wide association studies (GWAS) performed using the wheat 15 K genotyping array, 20 SNPs located on chromosomes 6D, 6A, 6B, 5A, 1B, 2A, 2B and 7A were revealed to be associated with leaf rust resistance. Genotyping with markers developed for known leaf rust resistance genes showed that most of the varieties contain genes Lr1, Lr3a, Lr9, Lr10, Lr17a, Lr20, Lr26 and Lr34, which are not currently effective against the pathogen. In the genome of three wheat varieties, gene Lr6Ai = 2 inherited from Th. intermedium was detected, which provides complete protection against the rust pathogen. It has been suggested that the QTL mapped to the chromosome 5AS of wheat cultivar Tulaikovskaya-zolotistaya, Tulaikovskaya-10, Samsar, and Volgouralskaya may be a new, previously undescribed locus conferring resistance to leaf rust. Obtained results also indicate that chromosome 1BL of the varieties Sonata, Otrada-Sibiri, Tertsiya, Omskaya-23, Tulaikovskaya-1, Obskaya-14, and Sirena may contain an unknown locus that provides a resistance response to local population.

CONCLUSIONS

This study provides new insights into the genetic basis of resistance to leaf rust in Russian spring wheat varieties. The SNPs significantly associated with leaf rust resistance can be used for the development and application of diagnostic markers in marker-assisted selection schemes.

Effects of Rht17 in combination with Vrn-B1 and Ppd-D1 alleles on agronomic traits in wheat in black earth and non-black earth regions

BACKGROUND

Plant height is an important wheat trait that is regulated by multiple genes, among which Rht is of the utmost value. In wheat, Rht-B1p (=Rht17) is a mutant allele of the Rht gene that encodes for a DELLA-protein and results in the development of gibberellin-insensitive plants with a dwarfing phenotype. The pleiotropic effects of dwarfing genes on yield are highly dependent on both the genetic background and the environmental conditions. In Russia, the Central Non-Black Earth Region and Krasnodar Krai are two economically important regions that require differing management for sustainable wheat production for food, feed and industry. The purpose of our study was to compare the pleiotropic effects of Rht-B1p on the main valuable agronomic traits in the F3:4 families of the spring bread wheat Chris Mutant/Novosibirskaya 67 in the genetic background of Vrn-B1a/vrn-B1 (spring/winter phenotype) and Ppd-D1a/Ppd-D1b (insensitivity/sensitivity to photoperiod) alleles in a field experiment in Moscow and Krasnodar Krai.

RESULTS

Plant height was reduced on average by 21 cm (28%) and 25 cm (30%), respectively; Ppd-D1a slightly strengthened the dwarfing effect in Moscow and mitigated it in Krasnodar Krai. Grain weight of the main spike was reduced by Rht-B1p in Moscow and to lesser extent in Krasnodar; Ppd-D1a and Vrn-B1a tended to partially compensate for this loss in Krasnodar Krai. Thousand grain weight was reduced on average by 5.3 g (16%) and 2.9 g (10%) in Moscow and Krasnodar Krai, respectively, but was partially compensated for by Ppd-D1a in Krasnodar Krai. Harvest index was increased due to Rht-B1p by 6 and 10% in Moscow and Krasnodar Krai, respectively. Rht-B1p resulted in a delay of heading by 1-2 days in Moscow. Ppd-D1a accelerated heading by 1 day and 6 days in Moscow and in Krasnodar Krai, respectively.

CONCLUSIONS

Rht-B1p could be introduced into wheat breeding along with dwarfing genes such as Rht-B1b and Rht-D1b. Special attention should be paid to its combination with Ppd-D1a and Vrn-B1a as regulators of developmental rates, compensators of adverse effects of Rht-B1p on productivity and enhancers of positive effect of Rht-B1p on harvest index.

Detection of Genomic Regions Associated with Resistance to Stem Rust in Russian Spring Wheat Varieties and Breeding Germplasm

Stem rust caused by Puccinia graminis f. sp. tritici Eriks. is a dangerous disease of common wheat worldwide. Development and cultivation of the varieties with genetic resistance is one of the most effective and environmentally important ways for protection of wheat against fungal pathogens. Field phytopathological screening and genome-wide association study (GWAS) were used for assessment of the genetic diversity of a collection of spring wheat genotypes on stem rust resistance loci. The collection consisting of Russian varieties of spring wheat and introgression lines with alien genetic materials was evaluated over three seasons (2016, 2017 and 2018) for resistance to the native population of stem rust specific to the West Siberian region of Russia. The results indicate that most varieties displayed from moderate to high levels of susceptibility to P. graminis; 16% of genotypes had resistance or immune response. In total, 13,006 single-nucleotide polymorphism (SNP) markers obtained from the Infinium 15K array were used to perform genome-wide association analysis. GWAS detected 35 significant marker-trait associations (MTAs) with SNPs located on chromosomes 1A, 2A, 2B, 3B, 5A, 5B, 6A, 7A and 7B. The most significant associations were found on chromosomes 7A and 6A where known resistance genes Sr25 and Sr6Ai = 2 originated from Thinopyrum ssp. are located. Common wheat lines containing introgressed fragments from Triticum timopheevii and Triticum kiharae were found to carry Sr36 gene on 2B chromosome. It has been suggested that the quantitative trait loci (QTL) mapped to the chromosome 5BL may be new loci inherited from the T. timopheevii. It can be inferred that a number of Russian wheat varieties may contain the Sr17 gene, which does not currently provide effective protection against pathogen. This is the first report describing the results of analysis of the genetic factors conferring resistance of Russian spring wheat varieties to stem rust.

Drought Stress Tolerance and Photosynthetic Activity of Alloplasmic Lines T. dicoccum x T. aestivum

Tetraploid species T. dicoccum Shuebl is a potential source of drought tolerance for cultivated wheat, including common wheat. This paper describes the genotyping of nine stable allolines isolated in the offspring from crossing of T. dicoccum x T. aestivum L. using 21 microsatellite (simple sequence repeats-SSR) markers and two cytoplasmic mitochondrial markers to orf256, rps19-p genes; evaluation of drought tolerance of allolines at different stages of ontogenesis (growth parameters, relative water content, quantum efficiency of Photosystem II, electron transport rate, energy dissipated in Photosystem II); and the study of drought tolerance regulator gene Dreb-1 with allele-specific PCR (AS-MARKER) and partial sequence analysis. Most allolines differ in genomic composition and T. dicoccum introgressions. Four allolines-D-b-05, D-d-05, D-d-05b, and D-41-05-revealed signs of drought tolerance of varying degrees. The more drought tolerant D-41-05 line was also characterized by Dreb-B1 allele introgression from T. dicoccum. A number of non-specific patterns and significant differences in allolines in regulation of physiological parameters in drought conditions is identified. Changes in photosynthetic activity in stress-drought are shown to reflect the level of drought tolerance of the forms studied. The contribution of different combinations of nuclear/cytoplasmic genome and alleles of Dreb-1 gene in allolines to the formation of stress tolerance and photosynthetic activity is discussed.

MIGREW: database on molecular identification of genes for resistance in wheat

Population structure of fungal infections in wheat differs between wheat varieties and environments. Taking into account evolution of host-pathogen interactions, genetic diversity of both wheat and fungus must be a monitored. In order to catalogue information to support need of wheat pathologists and breeders, who use conventional methods and Molecular Assisted Selection (MAS) techniques, we have developed the Molecular Identification of Genes for Resistance in Wheat (MIGREW) database. The main goal of this database is to support wheat breeding efforts to develop immunity to rusts and powdery mildew. MIGREW is also focused on effectiveness of wheat resistance genes in different regions of Russia to provide users relevant information on the rapidly changing population structure of pathogens.

Features of the organization of bread wheat chromosome 5BS based on physical mapping

BACKGROUND

The IWGSC strategy for construction of the reference sequence of the bread wheat genome is based on first obtaining physical maps of the individual chromosomes. Our aim is to develop and use the physical map for analysis of the organization of the short arm of wheat chromosome 5B (5BS) which bears a number of agronomically important genes, including genes conferring resistance to fungal diseases.

RESULTS

A physical map of the 5BS arm (290 Mbp) was constructed using restriction fingerprinting and LTC software for contig assembly of 43,776 BAC clones. The resulting physical map covered ~ 99% of the 5BS chromosome arm (111 scaffolds, N50 = 3.078 Mb). SSR, ISBP and zipper markers were employed for anchoring the BAC clones, and from these 722 novel markers were developed based on previously obtained data from partial sequencing of 5BS. The markers were mapped using a set of Chinese Spring (CS) deletion lines, and F2 and RICL populations from a cross of CS and CS-5B dicoccoides. Three approaches have been used for anchoring BAC contigs on the 5BS chromosome, including clone-by-clone screening of BACs, GenomeZipper analysis, and comparison of BAC-fingerprints with in silico fingerprinting of 5B pseudomolecules of T. dicoccoides. These approaches allowed us to reach a high level of BAC contig anchoring: 96% of 5BS BAC contigs were located on 5BS. An interesting pattern was revealed in the distribution of contigs along the chromosome. Short contigs (200-999 kb) containing markers for the regions interrupted by tandem repeats, were mainly localized to the 5BS subtelomeric block; whereas the distribution of larger 1000-3500 kb contigs along the chromosome better correlated with the distribution of the regions syntenic to rice, Brachypodium, and sorghum, as detected by the Zipper approach.

CONCLUSION

The high fingerprinting quality, LTC software and large number of BAC clones selected by the informative markers in screening of the 43,776 clones allowed us to significantly increase the BAC scaffold length when compared with the published physical maps for other wheat chromosomes. The genetic and bioinformatics resources developed in this study provide new possibilities for exploring chromosome organization and for breeding applications.

Dataset of the HOX1 gene sequences of the wheat polyploids and their diploid relatives

The TaHOX-1 gene of common wheat Triticum aestivum L. (BAD-genome) encodes transcription factor (HD-Zip I) which is characterized by the presence of a DNA-binding homeodomain (HD) with an adjacent Leucine zipper (LZ) motif. This gene can play a role in adapting plant to a variety of abiotic stresses, such as drought, cold, salinity etc., which strongly affect wheat production. However, it's both functional role in stress resistance and divergence during wheat evolution has not yet been elucidated. This data in brief article is associated with the research paper "Structural and functional divergence of homoeologous copies of the TaHOX-1 gene in polyploid wheats and their diploid ancestors". The data set represents a recent survey of the primary HOX-1 gene sequences isolated from the first wheat allotetraploids (BA-genome) and their corresponding Triticum and Aegilops diploid relatives. Specifically, we provide detailed information about the HOX-1 nucleotide sequences of the promoter region and both nucleotide and amino acid sequences of the gene. The sequencing data used here is available at DDBJ/EMBL/GenBank under the accession numbers MG000630-MG000698.

Evolution of VRN-1 homoeologous loci in allopolyploids of Triticum and their diploid precursors

BACKGROUND

The key gene in genetic system controlling the duration of the vegetative period in cereals is the VRN1 gene, whose product under the influence of low temperature (vernalization) promotes the transition of the apical meristem cells into a competent state for the development of generative tissues of spike. As early genetic studies shown, the dominant alleles of this gene underlie the spring forms of plants that do not require vernalization for this transition. In wheat allopolyploids various combinations of alleles of the VRN1 homoeologous loci (VRN1 homoeoalleles) provide diversity in such important traits as the time to heading, height of plants and yield. Due to genetical mapping of VRN1 loci it became possible to isolate the dominant VRN1 alleles and to study their molecular structure compared with the recessive alleles defining the winter type of plants. Of special interest is the process of divergence of VRN1 loci in the course of evolution from diploid ancestors to wheat allopolyploids of different levels of ploidy.

RESULTS

Molecular analysis of VRN1 loci allowed to establish that various dominant alleles of these loci appeared as a result of mutations in two main regulatory regions: the promoter and the first intron. In the diploid ancestors of wheat, especially, in those of A- genome (T. boeoticum, T. urartu), the dominant VRN1 alleles are rare in accordance with a limited distribution of spring forms in these species. In the first allotetraploid wheat species including T. dicoccoides, T. araraticum (T. timopheevii), the spring forms were associated with a new dominant alleles, mainly, within the VRN-A1 locus. The process of accumulation of new dominant alleles at all VRN1 loci was significantly accelerated in cultivated wheat species, especially in common, hexaploid wheat T. aestivum, as a result of artificial selection of spring forms adapted to different climatic conditions and containing various combinations of VRN1 homoeoalleles.

CONCLUSIONS

This mini-review summarizes data on the molecular structure and distribution of various VRN1 homoeoalleles in wheat allopolyploids and their diploid predecessors.

Fine organization of genomic regions tagged to the 5S rDNA locus of the bread wheat 5B chromosome

BACKGROUND

The multigene family encoding the 5S rRNA, one of the most important structurally-functional part of the large ribosomal subunit, is an obligate component of all eukaryotic genomes. 5S rDNA has long been a favored target for cytological and phylogenetic studies due to the inherent peculiarities of its structural organization, such as the tandem arrays of repetitive units and their high interspecific divergence. The complex polyploid nature of the genome of bread wheat, Triticum aestivum, and the technically difficult task of sequencing clusters of tandem repeats mean that the detailed organization of extended genomic regions containing 5S rRNA genes remains unclear. This is despite the recent progress made in wheat genomic sequencing. Using pyrosequencing of BAC clones, in this work we studied the organization of two distinct 5S rDNA-tagged regions of the 5BS chromosome of bread wheat.

RESULTS

Three BAC-clones containing 5S rDNA were identified in the 5BS chromosome-specific BAC-library of Triticum aestivum. Using the results of pyrosequencing and assembling, we obtained six 5S rDNA- containing contigs with a total length of 140,417 bp, and two sets (pools) of individual 5S rDNA sequences belonging to separate, but closely located genomic regions on the 5BS chromosome. Both regions are characterized by the presence of approximately 70-80 copies of 5S rDNA, however, they are completely different in their structural organization. The first region contained highly diverged short-type 5S rDNA units that were disrupted by multiple insertions of transposable elements. The second region contained the more conserved long-type 5S rDNA, organized as a single tandem array. FISH using probes specific to both 5S rDNA unit types showed differences in the distribution and intensity of signals on the chromosomes of polyploid wheat species and their diploid progenitors.

CONCLUSION

A detailed structural organization of two closely located 5S rDNA-tagged genomic regions on the 5BS chromosome of bread wheat has been established. These two regions differ in the organization of both 5S rDNA and the neighboring sequences comprised of transposable elements, implying different modes of evolution for these regions.

Features of Ppd-B1 expression regulation and their impact on the flowering time of wheat near-isogenic lines

BACKGROUND

Photoperiod insensitive Ppd-1a alleles determine early flowering of wheat. Increased expression of homoeologous Ppd-D1a and Ppd-A1a result from deletions in the promoter region, and elevated expression of Ppd-B1a is determined by an increased copy number.

RESULTS

In this study, using bread wheat cultivars Sonora and PSL2, which contrast in flowering time, and near-isogenic lines resulting from their cross, "Ppd-m" and "Ppd-w" with Ppd-B1a introgressed from Sonora, we investigated the putative factors that influence Ppd-B1a expression. By analyzing the Ppd-B1a three distinct copies, we identified an indel and the two SNPs, which distinguished the investigated allele from other alleles with a copy number variation. We studied the expression of the Ppd-A1, Ppd-B1a, and Ppd-D1 genes along with genes that are involved in light perception (PhyA, PhyB, PhyC) and the flowering initiation (Vrn-1, TaFT1) and discussed their interactions. Expression of Ppd-B1a in the "Ppd-m" line, which flowered four days earlier than "Ppd-w", was significantly higher. We found PhyC to be up-regulated in lines with Ppd-B1a alleles. Expression of PhyC was higher in "Ppd-m". Microsatellite genotyping demonstrated that in the line "Ppd-m", there is an introgression in the pericentromeric region of chromosome 5B from the early flowering parental Sonora, while the "Ppd-w" does not have this introgression. FHY3/FAR1 is known to be located in this region. Expression of the transcription factor FHY3/FAR1 was higher in the "Ppd-m" line than in "Ppd-w", suggesting that FHY3/FAR1 is important for the wheat flowering time and may cause earlier flowering of "Ppd-m" as compared to "Ppd-w".

CONCLUSIONS

We propose that there is a positive bidirectional regulation of Ppd-B1a and PhyC with an FHY3/FAR1 contribution. The bidirectional regulation can be proposed for Ppd-A1a and Ppd-D1a. Using in silico analysis, we demonstrated that the specificity of the Ppd-B1 regulation compared to that of homoeologous genes involves not only a copy number variation but also distinct regulatory elements.

Identification of new heading date determinants in wheat 5B chromosome

BACKGROUND

Variability of heading date may assist in wheat adaptation to local environments. Thereafter, discovery of new heading date determinants is important for cereal improvement. In this study we used common wheat cultivar Chinese Spring (CS) and the substitution line of CS with 5B chromosome from T. dicoccoides (CS-5Bdic), different in their heading date by two weeks, to detect determinants of heading date on 5B chromosome.

RESULTS

The possible influence of the VRN-B1 gene, the most powerful regulator of flowering, located on 5B chromosome, to differences in heading time between CS and CS-5Bdic was studied. The sequencing of this gene from CS-5Bdic showed that an insertion of a nucleotide triplet produced an additional amino acid in the corresponding protein. No changes in the transcription levels of each homoeologous VRN-1 loci were found in CS-5Bdic by comparison with CS. To ascertain the loci determining heading date difference, a set of 116 recombinant inbred 5В chromosomal lines as a result of hybridization of CS with CS-5Bdic were developed and their heading dates were estimated. Using the Illumina Infinium 15 k Wheat platform, 379 5B-specific polymorphic markers were detected and a genetic map with 82 skeletal markers was constructed. Phenotype (heading date) - genotype association analysis revealed seventy eight markers in pericentromeric region of 5B chromosome significantly associated with heading date variation. Based on this estimation and synteny with model crop genomes we identified the three best candidate genes: WRKY, ERF/AP2 and FHY3/FAR1.

CONCLUSIONS

We supposed that the difference in activity of WRKY, ERF/AP2 and/or FHY3/FAR1 transcription factors between CS and CS-5Bdic to be a probable reason for the observed difference in heading dates. Data obtained in this study provide a good basis for the subsequent investigation of heading time pathways in wheat.

[The effect of the succinic acid preparation on the dynamics of neurological and emotional disturbances in patients with dorsopathy]

OBJECTIVE

To study the dynamics of neurological and emotional disturbances in patients with dorsopathy treated with cytoflavin.

MATERIAL AND METHODS

We examined 120 patients aged from 21 to 55 years, mean age 38±9 years. All patients received nonsteroid anti-inflammatory drugs, myorelaxants, vitamins. The main group comprised 67 patients who received cytoflavin (10ml of the solution in one injection once a day in 200 ml of isotonic solution of sodium chloride intravenously in drops in the morning during 10 days) in addition to standard treatment. The comparison group included 53 patients who received standard treatment during 10 days.

RESULTS AND CONCLUSION

The use of cytoflavin allowed earlier arresting of the pain syndrome, restored the disturbed sensitivity, improved emotional status and decreased the severity of a neuropathic pain component.

VRN-1 gene- associated prerequisites of spring growth habit in wild tetraploid wheat T. dicoccoides and the diploid A genome species

BACKGROUND

In order to clarify the origin of spring growth habit in modern domesticated wheat, allelic variability of the VRN-1 gene was investigated in a wide set of accessions of the wild tetraploid species Triticum dicoccoides (BBAA), together with diploid species T. monococcum, T. boeoticum and T. urartu, presumable donors of the A genome to polyploid wheats.

RESULTS

No significant variation was found at the VRN-B1 locus of T. dicoccoides, whereas at VRN-A1 a number of previously described alleles were found with small deletions in the promoter (VRN-A1b, VRN-A1d) or a large deletion in the first (1st) intron (VRN-A1L). The diploid A genome species were characterized by their own set of VRN-1 alleles including previously described VRN-A1f and VRN-A1h alleles with deletions in the promoter region and the VRN-A1ins allele containing a 0.5 kb insertion in the 1st intron. Based on the CAPS screening data, alleles VRN-A1f and VRN-A1ins were species-specific for T. monococcum, while allele VRN-A1h was specific for T. boeoticum. Different indels were revealed in both the promoter and 1(st) intron of the recessive VRN-A1u allele providing specific identification of T. urartu, the proposed donor of the A genome to modern wheat. We found that alleles VRN-A1b and VRN-A1h, previously described as dominant, have either no or weak association with spring growth habit, while in some diploid accessions this habit was associated with the recessive VRN-A1 allele.

CONCLUSIONS

Spring growth habit in diploid wheats was only partially associated with indels in regulatory regions of the VRN-1 gene. An exception is T. monococcum where dominant mutations in both the promoter region and, especially, the 1st intron were selected during domestication resulting in a greater variety of spring forms. The wild tetraploid T. dicoccoides had a distinct set of VRN-A1 alleles compared to the diploids in this study, indicating an independent origin of spring tetraploid forms that likely occurred after combining of diploid genomes. These alleles were subsequently inherited by cultivated polyploid (tetraploid and hexaploid) descendants.

(GAA)n microsatellite as an indicator of the A genome reorganization during wheat evolution and domestication

Although the wheat A genomes have been intensively studied over past decades, many questions concerning the mechanisms of their divergence and evolution still remain unsolved. In the present study we performed comparative analysis of the A genome chromosomes in diploid (Triticum urartu Tumanian ex Gandilyan, 1972, Triticum boeoticum Boissier, 1874 and Triticum monococcum Linnaeus, 1753) and polyploid wheat species representing two evolutionary lineages, Timopheevi (Triticum timopheevii (Zhukovsky) Zhukovsky, 1934 and Triticum zhukovskyi Menabde & Ericzjan, 1960) and Emmer (Triticum dicoccoides (Körnicke ex Ascherson & Graebner) Schweinfurth, 1908, Triticum durum Desfontaines, 1798, and Triticum aestivum Linnaeus, 1753) using a new cytogenetic marker - the pTm30 probe cloned from Triticum monococcum genome and containing (GAA)56 microsatellite sequence. Up to four pTm30 sites located on 1AS, 5AS, 2AS, and 4AL chromosomes have been revealed in the wild diploid species, although most accessions contained one-two (GAA)n sites. The domesticated diploid species Triticum monococcum differs from the wild diploid species by almost complete lack of polymorphism in the distribution of (GAA)n site. Only one (GAA)n site in the 4AL chromosome has been found in Triticum monococcum. Among three wild emmer (Triticum dicoccoides) accessions we detected 4 conserved and 9 polymorphic (GAA)n sites in the A genome. The (GAA)n loci on chromosomes 2AS, 4AL, and 5AL found in of Triticum dicoccoides were retained in Triticum durum and Triticum aestivum. In species of the Timopheevi lineage, the only one, large (GAA)n site has been detected in the short arm of 6A(t) chromosome. (GAA)n site observed in Triticum monococcum are undetectable in the A(b) genome of Triticum zhukovskyi, this site could be eliminated over the course of amphiploidization, while the species was established. We also demonstrated that changes in the distribution of (GAA)n sequence on the A-genome chromosomes of diploid and polyploid wheats are associated with chromosomal rearrangements/ modifications, involving mainly the NOR (nucleolus organizer region)-bearing chromosomes, that took place during the evolution of wild and domesticated species.

[Detection of genetic determinants that define the difference of near-isogenic Triticum aestivum L. Lines in photoperiodic sensitivity]

Identification of genetic determinants that define different degrees of line sensitivity to the photoperiod was conducted on material of near-isogenic lines of the soft hexaploid wheat Triticum aestivum L. using SSR markers and markers specific to the Vrn and Ppd genes. It was established that the Ppd-s line contains a dominant Ppd-Dla allele located on chromosome 2D. This allele is characterized by a vast deletion in the gene promoter region. For two other lines (Ppd-m and Ppd-w), introgression of the Ppd-B1 gene on chromosome 2B was shown from the parental Sonora variety, which is slightly sensitive to the length of the day; however, the previously described Ppd-Bla. 1 allele was not found. Another polymorphism that can cause weak photoperiodic sensitivity, an increased amount of the Ppd-B1 gene copies, was detected for these lines.

[Efficiency of mexidol in patients with endocrine polyneuropathy]

OBJECTIVE

To evaluate the efficacy of mexidol and necessity of using it in patients with endocrine polyneuropathies caused by primary hypothyroidism (PPHT). MATERIALS AND METHODS; We have examined 51 patients with confirmed diagnosis of PPHT and assessed their neurological status and indicators of metabolic homeostasis before and after treatment. Electroneuromyography (ENMG) was performed to assess the status of the peripheral nervous system.

RESULTS

The results indicate the presence of endocrine disorders of obligate metabolic homeostasis in patients with polyneuropathies. Antioxidants, in particular, mexidol, in a complex with other drugs can be used in the treatment of these disorders. Worsening of ENMG-parameters, demonstrating a trend towards the normalization in response to treatment antioxidants, are characteristics of this pathology.

CONCLUSION

The efficacy of mexidol in patients with PPHT has been confirmed.

[A comparative genetic and cytogenetic mapping of wheat chromosome 5B using introgression lines]

The genetic map of chromosome 5B has been constructed by using microsatellite (SSR) analysis of 381 plants from the F2 population produced by cross of the Chinese Spring (CS) and Renan cultivars. Initially, 180 SSR markers for the common wheat 5B chromosome have been used for analysis of these cultivars. The 32 markers able to detect polymorphism between these cultivars have been located on the genetic map of chromosome 5B. Cytogenetic mapping has involved a set of CS 5B chromosome deletion lines. Totally, 51 SSR markers have been located in ten regions (deletion bins) of this chromosome by SSR analysis of these deletion lines. Five genes--TaCBFIIIc-B10, Vrn--B1, Chi--B1, Skr, and Ph1--have been integrated into the cytogenetic map of chromosome 5B using the markers either specific of or tightly linked to the genes in question. Com- parison of the genetic and cytogenetic maps suggests that recombination is suppressed in the pericentromeric region of chromosome 5B, especially in the short arm segment. The 18 markers localized to deletion bins 5BL16-0.79-1.00 and 5BL8-0.66-0.79 have been used to analyze common wheat introgression lines L842, L5366-180, L73/00i, and L21-4, carrying fragments of alien genomes in the terminal region of 5B long arm. L5366-180 and L842 lines carry a fragment of the Triticum timopheevii 5GL chromosome, while L73/00i ? L21-4 lines, a fragment of the Aegilopsspeltoides 5SL chromosome. As has been shown, the translocated fragments in these four lines are of different lengths, allowing bin 5BL18-0.66-0.79 to be divided into three shorter regions. The utility of wheat introgression lines carrying alien translocations for increasing the resolution of cytogenetic mapping is discussed.

[Comparative Characteristic of Triticum aestivum/Triticum durum and Triticum aestivum/Triticum dicoccum hybrid lines by genomic composition and resistance to fungal diseases under different environmental conditions]

The genetic diversity of common wheat hybrid lines Triticum aestivum/Triticum durum and Triticum aestivum/Triticum dicoccum (2n = 42, F(6-7)) using chromosome-specific microsatellite (SSR) markers and C-staining of chromosomes was studied. Cluster analysis of data obtained by 42 SSR markers indicated that the hybrid lines can be broken into three groups according to their origin. There were two cases of complete genetic similarity between lines 183(2)-2/184(1)-6 and-208-3/213-1, which were obtained using common wheat as the parental plants. In cross combinations, when the stabilization of the nuclear genome of hexaploid lines occurred against a background of the cytoplasmic genome of tetraploid wheats, there was a high level of divergence between sister lines, in some cases exceeding 50%. The evaluation of the degree of susceptibility of the lines to powdery mildew, leaf and stem rust, and septoria leafblotch was performed under different environmental conditions. It was shown that resistance to powdery mildew and leaf rust significantly depended on the region where assays were conducted. An evaluation of the field data showed that he lines 195-3, 196-1, and 221-1 with T. durum genetic material displayed complex resistance to fungal pathogens in Western Siberia and the Republic of Belarus. For lines 195-3 and 196-1, one shows a possible contribution of chromosomes 4B and 5B in the formation of complex resistance to diseases. Hybrid lines with complex resistance can be used to expand the genetic diversity of modern common wheat cultivars for genes of immunity.

[Epigenetic regulation of expression of vernalization genes]

We reviewed the mechanisms of epigenetic regulation of vernalization genes of plants which control the transition to the generative stage, depending on the low temperatures. Based on the example of FLC-gene of Arabidopsis, the involvement of the PR2 repression complex and non-coding RNAs in these mechanisms has been shown. On the basis of our own and other data, the authors suggest a similar mechanism of regulation of Vrn-1 gene of cereals.

[The impact of Ty3-gypsy group retrotransposon Lila on D-genome specificity of wheat Triticum aestivum L]

An analysis of the primary structure of BAC clone 112D20 T. aestivum, that contains D-genome specific Ty3-gypsy-retrotransposon Lila is presented. PCR analysis of nulli-tetrasomic and deletion lines of T. aestivum allowed to localize this BAC clone in the distal region of the long arm of chromosome 5D. Characteristic feature of BAC clone 112D20 is a high concentration of Ty3-gypsy-retrotransposons (61.7%), and low content of the genes (1.2%). Only a single open reading frame was revealed homologous to an unknown gene of Ae. tauschii. Specific to the D-genome Ty3-gypsy-retrotransposon Lila in the BAC clone 112D20 is 14 kb in length and contains unequal in size long terminal repeats. The data of in situ hybridization and PCR analysis of different Triticeae species suggest that this retroelement was amplified within the ancestral species of Ae. tauschii, the donor D-genome. The suggested time of amplification based on estimation of insertion time of Lila 112D20 is 1.7 million years, which corresponds to the formation of the first allopolyploid forms of wheat. Based on comparison with the previously obtained data, it is concluded that the amplification ofretroelements specific to each genome of wheat took place during formation of the diploid progenitors of these genomes.

[Construction and study of leaf rust-resistant common wheat lines with translocations of Aegilops speltoides Tausch]

Genotyping was performed for the leaf rust-resistant line 73/00i (Triticum aestivum x Aegilops speltoides). Fluorescence in situ hybridization (FISH) with probes Spelt1 and pSc119.2 in combination with microsatellite analysis were used to determine the locations and sizes of the Ae. speltoides genetic fragments integrated into the line genome. Translocations were identified in the long arms of chromosomes 5B and 6B and in the short arm of chromosome 1B. The Spelt1 and pSc119.2 molecular cytological markers made it possible to rapidly establish lines with single translocation in the long arms of chromosomes 5B and 6B. The line carrying the T5BS x 5BL-5SL translocation was highly resistant to leaf rust, and the lines carrying the T6BS x 6BL-6SL translocation displayed moderate resistance. The translocations differed in chromosomal location from known leaf resistance genes transferred into common wheat from Ae. speltoides. Hence, it was assumed that new genes were introduced into the common wheat genome from Ae. speltoides. The locus that determined high resistance to leaf rust and was transferred into the common wheat genome from the long arm of Ae. speltoides chromosome 5S by the T5BS x 5BL-5SL translocation was preliminarily designated as LrAsp5.

The impact of Ty3-gypsy group LTR retrotransposons Fatima on B-genome specificity of polyploid wheats

BACKGROUND

Transposable elements (TEs) are a rapidly evolving fraction of the eukaryotic genomes and the main contributors to genome plasticity and divergence. Recently, occupation of the A- and D-genomes of allopolyploid wheat by specific TE families was demonstrated. Here, we investigated the impact of the well-represented family of gypsy LTR-retrotransposons, Fatima, on B-genome divergence of allopolyploid wheat using the fluorescent in situ hybridisation (FISH) method and phylogenetic analysis.

RESULTS

FISH analysis of a BAC clone (BAC_2383A24) initially screened with Spelt1 repeats demonstrated its predominant localisation to chromosomes of the B-genome and its putative diploid progenitor Aegilops speltoides in hexaploid (genomic formula, BBAADD) and tetraploid (genomic formula, BBAA) wheats as well as their diploid progenitors. Analysis of the complete BAC_2383A24 nucleotide sequence (113,605 bp) demonstrated that it contains 55.6% TEs, 0.9% subtelomeric tandem repeats (Spelt1), and five genes. LTR retrotransposons are predominant, representing 50.7% of the total nucleotide sequence. Three elements of the gypsy LTR retrotransposon family Fatima make up 47.2% of all the LTR retrotransposons in this BAC. In situ hybridisation of the Fatima_2383A24-3 subclone suggests that individual representatives of the Fatima family contribute to the majority of the B-genome specific FISH pattern for BAC_2383A24. Phylogenetic analysis of various Fatima elements available from databases in combination with the data on their insertion dates demonstrated that the Fatima elements fall into several groups. One of these groups, containing Fatima_2383A24-3, is more specific to the B-genome and proliferated around 0.5-2.5 MYA, prior to allopolyploid wheat formation.

CONCLUSION

The B-genome specificity of the gypsy-like Fatima, as determined by FISH, is explained to a great degree by the appearance of a genome-specific element within this family for Ae. speltoides. Moreover, its proliferation mainly occurred in this diploid species before it entered into allopolyploidy.Most likely, this scenario of emergence and proliferation of the genome-specific variants of retroelements, mainly in the diploid species, is characteristic of the evolution of all three genomes of hexaploid wheat.

[Development of commercially valuable traits in hexaploid triticale lines with Aegilops introgressions as dependent on the genome composition]

Introgressive hybridization is an efficient means to improve the genetic diversity of cultivated cereals, including triticale. To identify the triticale lines with Aegilops introgressions, genotyping was carried out with ten lines obtained by crossing hexaploid triticale with genome-substitution forms of the common wheat cultivar Avrora: Avrolata (AABBUU), Avrodes (AABBSS), and Avrotika (AABBTT). The genome composition of the triticale lines was studied by in situ hybridization, and recombination events involving Aegilops and/or common wheat chromosomes were assumed for nine out of the ten lines. Translocations involving rye chromosomes were not observed. Substitutions for rye chromosomes were detected in two lines resulting from crosses with Avrolata. Genomic in situ hybridization (GISH) with Ae. umbellulata DNA and molecular genetic analysis showed that chromosome 1R was substituted with Ae. umbellulata chromosome 1U in one of the lines and that 2R(2U) substitution took place in the other line. Fluorescence in situ hybridization (FISH) with the Spelt 1 and pSc119.2 probes revealed a translocation from Ae. speltoides to the long arm of chromosome 1B in one of the two lines resulting from crosses with Avrodes and a translocation in the long arm of chromosome 7B in the other line. In addition, the pSc119.2 probe revealed chromosome 1B rearrangements in four lines resulting from crosses with Avrolata and in a line resulting from crosses with Avrotika. The lines were tested for main productivity parameters. A negative effect on all productivity parameters was demonstrated for Ae. umbellulata chromosome 2U. The overwinter survival in all of the lines was similar to or even higher than in the original triticale cultivars. A substantial increase in winter resistance as compared with the parental cultivar was observed for the line carrying the T7BS-7SL translocation. The line with the 1R(1U) chromosome substitution seemed promising for the baking properties of triticale.

[Comparative cytological and molecular analysis of introgressive common wheat lines containing genetic material of Triticum timopheevii Zhur]

A total of 40 introgressive lines of common wheat (2n = 42) Triticum aestivum L x T. timopheevii Zhuk., resistant to brown rust and partly to powdery mildew, were examined. Based on cytological analysis of meiosis in pollen mother cells (PMC), hybrid lines were subdivided into two groups characterized by either stable or unstable meiosis. In cytologically stable lines, chromosome configuration at the MI stage of meiosis was mostly bivalent (21II) with small proportion of defect cells (almost 10%), which at most contained two univalents (20II + + 21). Cytologically unstable group was comprised of the lines, containing high proportions of cells with abnormal chromosome pairing in meiotic PMC, as well as the cells with multivalents, and the lines containing aneuploid plants. Localization of the T. timopheevii fragments performed with the use of SSR markers showed that the lines with unstable meiosis were characterized by higher numbers of introgressions compared to stable lines. The influence of certain chromosomes of T. timopheevii on chromosome pairing stability was also demonstrated. In cytologically unstable lines, the increased frequency of 2A substitutions along with the high frequency of introgression of T. timopheevii genetic material into chromosome 7A was observed. Multivalents were scored in all cases of introgression in chromosome 7A. It was suggested that the reason for the genome instability in hybrid forms lied in insufficient compensating ability of certain T. timopheevii chromosomes and/or their parts, involved into recombination processes.

[Chromosome synteny of the A genome of two evolutionary wheat lines]

In order to estimate synteny between A(t) and A polyploid wheat genomes belonging to different evolutionary lines (Timopheevi and Emmer), saturation of chromosome maps of Triticum timopheevii A(t) genome by molecular markers has been conducted. Totally, 179 EST-SSR and 48 genomic SSR-markers have been used with the following integration of 13 and 7 markers correspondingly into chromosome maps of A(t) genome. EST-SSR showed higher transferability and lower polymorphism than genomic SSR markers. The chromosome maps designed were compared to maps of homoeologous chromosome group of the T. aestivum A genome. No disturbances of colinearity, i.e., of the order of markers within the chromosome segments on which they had been previously mapped, were observed. According to the quantity assessment of markers amplifying in homoeologous chromosomes, the maximum divergence was detected in two groups (4A(t)/4A and 3A(t)/3A) among the seven chromosomes examined in the A(t) and A genomes. Comparison of molecular genetic mapping results with the published results of studying meiosis of F1 hybrids and the frequency of chromosomes substitution in introgressive T. aestivum x T. timopheevii lines suggest that individual chromosomes of the At and A genomes evolve differently. Translocations were shown to introduce the major impact on the divergence of 4A(t)/4A and 6A(t)/6A chromosomes, while mutations of the primary DNA structure, on the divergence of homoeologous group 3 chromosomes. The level of reorganization of other chromosomes during the evolution in the A(t) and A genomes was significantly lower.

Isolation and sequence analysis of the wheat B genome subtelomeric DNA

Background

Telomeric and subtelomeric regions are essential for genome stability and regular chromosome replication. In this work, we have characterized the wheat BAC (bacterial artificial chromosome) clones containing Spelt1 and Spelt52 sequences, which belong to the subtelomeric repeats of the B/G genomes of wheats and Aegilops species from the section Sitopsis.

Results

The BAC library from Triticum aestivum cv. Renan was screened using Spelt1 and Spelt52 as probes. Nine positive clones were isolated; of them, clone 2050O8 was localized mainly to the distal parts of wheat chromosomes by in situ hybridization. The distribution of the other clones indicated the presence of different types of repetitive sequences in BACs. Use of different approaches allowed us to prove that seven of the nine isolated clones belonged to the subtelomeric chromosomal regions. Clone 2050O8 was sequenced and its sequence of 119 737 bp was annotated. It is composed of 33% transposable elements (TEs), 8.2% Spelt52 (namely, the subfamily Spelt52.2) and five non-TE-related genes. DNA transposons are predominant, making up 24.6% of the entire BAC clone, whereas retroelements account for 8.4% of the clone length. The full-length CACTA transposon Caspar covers 11 666 bp, encoding a transposase and CTG-2 proteins, and this transposon accounts for 40% of the DNA transposons. The in situ hybridization data for 2050O8 derived subclones in combination with the BLAST search against wheat mapped ESTs (expressed sequence tags) suggest that clone 2050O8 is located in the terminal bin 4BL-10 (0.95-1.0). Additionally, four of the predicted 2050O8 genes showed significant homology to four putative orthologous rice genes in the distal part of rice chromosome 3S and confirm the synteny to wheat 4BL.

Conclusion

Satellite DNA sequences from the subtelomeric regions of diploid wheat progenitor can be used for selecting the BAC clones from the corresponding regions of hexaploid wheat chromosomes. It has been demonstrated for the first time that Spelt52 sequences were involved in the evolution of terminal regions of common wheat chromosomes. Our research provides new insights into the microcollinearity in the terminal regions of wheat chromosomes 4BL and rice chromosome 3S.

[Use of SNP markers developed for allopolyploid wheat]

In this work, we analyzed 54 domestic cultivars of hexaploid (common) wheat Triticum aestivum L. (AABBDD genome) and accessions of tetraploid wheats of the Timopheevi group (AAGG) and rye Secale cereale (RR) using 21 SNP markers for common wheat. It was demonstrated that application of the SNP markers developed and verified for particular common wheat cultivars in allele-specific PCR analysis of other cultivars with different geographic origins could lead to an incorrect estimation of the similarity between the genotypes tested. The studied SNP markers of common wheat are inappropriate for analyzing genomes of other cereal species, in particular, Timopheevi wheats and rye S. cereale.

Relationship between homoeologous regulatory and structural genes in allopolyploid genome - a case study in bread wheat

BACKGROUND

The patterns of expression of homoeologous genes in hexaploid bread wheat have been intensively studied in recent years, but the interaction between structural genes and their homoeologous regulatory genes remained unclear. The question was as to whether, in an allopolyploid, this interaction is genome-specific, or whether regulation cuts across genomes. The aim of the present study was cloning, sequence analysis, mapping and expression analysis of F3H (flavanone 3-hydroxylase - one of the key enzymes in the plant flavonoid biosynthesis pathway) homoeologues in bread wheat and study of the interaction between F3H and their regulatory genes homoeologues - Rc (red coleoptiles).

RESULTS

PCR-based cloning of F3H sequences from hexaploid bread wheat (Triticum aestivum L.), a wild tetraploid wheat (T. timopheevii) and their putative diploid progenitors was employed to localize, physically map and analyse the expression of four distinct bread wheat F3H copies. Three of these form a homoeologous set, mapping to the chromosomes of homoeologous group 2; they are highly similar to one another at the structural and functional levels. However, the fourth copy is less homologous, and was not expressed in anthocyanin pigmented coleoptiles. The presence of dominant alleles at the Rc-1 homoeologous loci, which are responsible for anthocyanin pigmentation in the coleoptile, was correlated with F3H expression in pigmented coleoptiles. Each dominant Rc-1 allele affected the expression of the three F3H homoeologues equally, but the level of F3H expression was dependent on the identity of the dominant Rc-1 allele present. Thus, the homoeologous Rc-1 genes contribute more to functional divergence than do the structural F3H genes.

CONCLUSION

The lack of any genome-specific relationship between F3H-1 and Rc-1 implies an integrative evolutionary process among the three diploid genomes, following the formation of hexaploid wheat. Regulatory genes probably contribute more to the functional divergence between the wheat genomes than do the structural genes themselves. This is in line with the growing consensus which suggests that although heritable morphological traits are determined by the expression of structural genes, it is the regulatory genes which are the prime determinants of allelic identity.