Background. As a result of global warming, climate change is now taking place, increasing the frequency and duration of droughts. Therefore, the development of new varieties with an increased drought resistance and adaptation to certain environmental conditions is of primary importance. The aim of this work was to modify the express method of drought resistance evaluation in peas at an early stage of plant growth and development, and to apply this method to test 50 accessions from the VIR global collection.

Materials and methods. Drought resistance studies involved garden pea accessions of different eco-geographic origin, which had been previously characterized in field tests in conditions of the Krasnodar Territory in 2017-2019. The roll-ups protocol was used for evaluating early drought resistance in the accessions. The stress intensity was modified by varying the concentration of sucrose in the solution used for growing of pea seedlings. To select an appropriate concentration, an osmotic pressure of 0.5 and 0.7 MPa was applied. As a result, the osmotic pressure of 0.5 MPa was chosen. The diagnostic criterion of the method is the radicle length index (RLI), that is, the ratio of the average radicle length of seedlings against a provocative background to the control values.

Results. The osmotically active solution led to significant reduction in the radicle length of pea seedlings. The studied accessions exhibited considerable genetic variability for early drought tolerance, the RLI value varied from 0.28 to 0.88. Sources of high drought resistance during the period of seedling growth have been identified. The correlation analysis showed the absence of a reliable relationship between the RLI and the crop structure indicators (correlation coefficients from r = +0.17 to r = -0.24).

Conclusion. By using the method of determining the relative drought tolerance at early stages of pea accessions development, one highly resistant (k-9333 from Morocco) and 10 resistant accessions (k-1495, k-9372, k-9401, k-9418, k-9733, k-9909, k-9934, k-9938, k-10072, and k-10116.) have been identified.

Background. Wheat leaf rust caused by Puccinia triticina Erikss. is a significant wheat disease in all regions of the Russian Federation. The genetic diversity of the cultivated wheat varieties regarding the type of resistance and genes that control it ensures reliable protection of this crop against the pathogen. The aim of this work was to characterize the diversity of new Russian varieties of winter and spring common wheat for leaf rust resistance genes (Lr-genes).

Materials and Methods. The research material was represented by 43 varieties of winter and 25 of spring wheat included in the State Register of Selection Achievements of the Russian Federation in 2018-2020.

Results. Using molecular markers, 18 Lr genes were identified: Lr1, Lr3, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, Lr25, Lr26, Lr28, Lr29, Lr34, Lr35, Lr37, Lr41 (39), Lr47 and Lr66. A phytopathological test was used to clarify the results of molecular analysis. Ninety-three percent of the studied wheat varieties were found to contain Lr genes, either separately or in combinations. These were the highly and partially effective genes Lr24, Lr9, and Lr19, adult plant resistance genes Lr34 and Lr37, and ineffective genes Lr1, Lr3, Lr10, Lr20, and Lr26. The Lr24 gene has been identified for the first time in Russian varieties. The spring variety ‘Leader 80’, harboring this gene, is recommended for cultivation in the West Siberian and East Siberian regions. An effective combination of Lr9 + Lr26 genes, individually overcome by the pathogen, was determined in the spring cultivar ‘Silach’, highly resistant to leaf rust. The Lr9 gene was found in the winter variety ‘Gerda’, which is recommended for cultivation in the North Caucasus region. Previously, the varieties with Lr9 were not grown in the North Caucasus. An increase in the number of leaf rust resistant accessions protected by the effective adult plant resistance gene Lr37 is noted among wheat varieties undergoing regional adaptation testing. Many of the identified Lr genes (Lr19, Lr24, Lr26, Lr34, Lr37) are linked with effective Sr genes (Sr25, Sr24, Sr31, Sr57, and Sr38), which additionally ensures stable genetic protection of wheat against stem rust.

Conclusions. The obtained information about representation of Lr genes in wheat varieties should be used in regional breeding programs. A timely replacement of genetically protected varieties allows stabilizing the populational composition of the phytopathogen and reducing the likelihood of epiphytotics.

Background. Modern production of sunflower seeds is currently based on the cultivation of high-yielding heterotic F₁ hybrids from crossbreeding of lines with cytoplasmic male sterility (CMS) of PET1-type and fertility restorer lines. The paternal parent serves as a donor of the nuclear Rf1 gene functional allele, which is responsible for pollen fertility restoration in F₁ plants. The detection of carriers of the Rf1 locus recessive and dominant alleles using diagnostic molecular markers accelerates breeding of female and male parental lines for creating hybrids.

Materials and methods. The material for the study included 75 lines of various origins from the VIR sunflower genetic collection as well as hybrids from crosses of VIR 116A sterile line with fertile lines differing in the type of cytoplasm (fertile or sterile) and the presence of molecular markers, most of which were linked to the Rf1 locus. For marker validation, two different approaches were used: either by analyzing associations between the ability of a line to restore pollen fertility and the presence of molecular markers in its genotype, or by estimating recombination frequency between the Rf1 locus and marker loci in four segregating hybrid populations.

Results. According to the obtained results, no markers demonstrated 100% efficiency in the analysis of the sample of genotypes. The ORS511 marker was most frequently observed among the lines presumably carrying the dominant allele Rf1. Pollen fertility of F₁ hybrids from interline crossings was 89-99%. The segregation for fertility/sterility in F₂ fitted the theoretical ratio of 3:1 expected in case of the monogenic control of the trait. The markers HRG01, HRG02 and ORS511 were linked to the fertility restoration trait, with recombination rates between Rf1 locus and markers varying in different cross combinations. The analysis of VIR 116А × VIR 740 and VIR 116А × RIL 130 hybrids showed that among the marker loci studied, the ORS511 was closest to the Rf1 locus Rf1 (recombination frequency of 2.2 and 3.3%, respectively). The recombination rate between the Rf1 and ORS511 loci equaled 7.5% in the cross VIR 116А × VIR 210 and 8.9% in VIR 116 × VIR 195.

Conclusion. The markers ORS511, HRG01 and HRG02 are the most efficient for the identification of alleles of the Rf1 gene and for the marker assisted selection in hybrid populations produced involving sunflower lines from the VIR collection.

Background. The development of heterotic hybrids based on cytoplasmic male sterility (CMS) is the leading strategy in breeding sorghum (Sorghum bicolor (L.) Moench). The trait of pollen fertility restoration in forms with CMS A1 (milo), predominantly used in sorghum breeding, is determined by at least two dominant complementary genes Rf1 and Rf2, and also gene Rf5. The development of accessible molecular markers of sorghum Rf genes is highly relevant for hybrid breeding, since they can significantly accelerate the process of creating female sterile forms (A lines), sterility maintainers (B lines) and pollen fertility restorers (R lines).

Material and methods. The studied material included 36 sorghum accessions from the VIR collection, which differed by the ability to restore pollen fertility in forms with A1-type CMS. The nucleotide polymorphism of 935 bp fragments of the PPR genes Sobic.002G057050, Sobic.002G054100, and Sobic.002G054200 located at the chromosome 2 was studied.

Results. The fragments obtained with the use of a pair of 2459403fw and 2459403 primers were 935 bp long and included parts of three genes: Sobic.002G057050, Sobic.002G054100, Sobic.002G054200. For identifying the sequence variant Sobic.002G057050-1090 associated with the Rf2 gene, Tru9 I restrictase was chosen, which allows obtaining a 572 bp fragment unique for all the studied R lines. Such a marker was found in 10 sorghum lines from West China and Kyrgyzstan, which are widely used in breeding as fertility restorers. The fragment was found neither in three lines with sterile cytoplasm and their fertile analogues, nor in 7 accessions of kafir sorghum, which lacked functional alleles of Rf genes.

Conclusions. It has been demonstrated that the marker can be used for selection and checking purity of R and B/A lines. It is also applicable for verifying hybridity of F₁ seeds and analyzing hybrid populations from crosses of R lines 924-4, 928-1, 929-3, 931-1, 933-1/6, 1237-3, 1243-2, 1251, 1150-1, F₁₀BC₂ with A lines Nizkorosloe 81s, А-83 and А-10598. It may be suggested that the ability to restore pollen fertility in R lines, which lack the marker CAPS- 572, is determined by another Rf gene. The studied 935 bp fragment of Sobic.002G057050 harbours 22 SNP, therefore the development of CAPS-markers for their identification and differentiation can be promising.