Nowadays in Russia and in the world, the problem of improving food security is becoming more and more urgent. One of the main crops grown worldwide is winter bread wheat. Varieties resistant to main leaf diseases can produce large grain yields. Thus, the study and identification of resistance genes are of great importance. The purpose of the current work was to estimate the gene pool of winter bread wheat from the CIMMYT collection (Mexico) according to the age brown rust Lr 34 resistance gene. In the study of collection samples, there have been used such methods as DNA extraction using CTAB, PCR, electrophoresis on agarose gels. As a result of the study, there has been identified a presence of a functional allele of the Lr 34 gene in 146 winter bread wheat samples out of 411 studied ones (sets 20th IWWYT-SA, 21th IWWYT-IRR, 25th FAWWON-IRR, 25th FAWWON-SA). There have been identified three samples with a heterozygous allelic state of the Lr 34 gene. There have been identified 232 samples with the non-functional Lr 34 gene allele. 30 winter bread wheat samples had no amplification of DNA fragments with the molecular marker csLV34, which means a significant microsatellite sequence variability for which the molecular marker was developed in their genotype. 121 out of 146 winter bread wheat samples with the functional brown rust Lr 34 resistance gene showed resistance in field conditions and in the infectious plots. The rest 25 samples with the Lr 34 gene belonged to the group of moderately resistant ones in the infectious plots. The identified 121 CIMMYT collection winter bread wheat varieties, with the Lr 34 gene possessing a resistant type of pathogen damage response (for example, 9919, 9921, 9928, 9809, 9811, 9812, 23, 24, 30, 262, 265, 266, etc.) have been recommended for use in leaf rust resistance pyramiding in future breeding programs.

One of the main problems in most of the world rice-growing regions is soil salinity. Rice is considered a saline sensitive crop, especially at the early stages of development and in the period of maturity. In the Rostov region, rice is grown in the south-eastern parts, where there are currently difficulties with the operation of the existing reclamation facilities. The problem of saline soils for this region is especially urgent, since a significant part of the arable lands has alkali complexes. In order to return the saline lands into exploitation, it is necessary to develop salt tolerant varieties, which, under crop rotation and maintenance, can contribute to soil desalinization. Due to the difficulty of determining salt tolerance only by estimating the phenotype, it is necessary to use molecular markers associated with this trait. Thus, the purpose of the current work was to identify one of the main Saltol QTL in breeding rice samples of the eighth generation (F8) obtained from hybridizing the donor variety NSYC Rc106 with Russian varieties. For that purpose, there have been used such marker-assisted selection methods as DNA isolation, polymerase chain reaction (PCR), electrophoresis on 2% agarose gels, gels’ coloring in ethidium bromide solution, photography in ultraviolet light and evaluation of the obtained electrophoregrams. As a result of the study of 398 breeding rice samples, there have been identified 67 samples with the functional allele of Saltol QTL (6865/3, 6874/2, Don 7343/4, Don 7343/5, Don 7343/6, Don 7343/7, Don 7343/8, Don 7343/9, Don 7343/10, Don 7337/1, Don 7337/3, Don 7337/4, Don 7337/5, Don 7337/6, Don 7337/7, Don 7337/8, etc.). There have been recommended to use these samples in the further breeding process in order to develop new salinity resistant rice varieties.

Rice is one of the most important crops in the world. Rice crops provide food for many people in Asia and the Pacific. In Russia, the production of this crop is concentrated in several regions, one of which is the Rostov region. The trend towards the greening of agriculture throughout the world and in Russia is becoming more and more stable. In order to combat weeds using an environmentally friendly herbicide-free technology, it is necessary to increase the water layer on simultaneous surviving rice plants. For such a strategy to work, it is necessary to develop varieties that are resistant to flooding. The purpose of the current study was to identify the allelic state of the Sub1A flood resistance gene in breeding rice samples. The objects of the study were 90 rice samples of the sixth generation, identified in hybrids obtained from crossing Russian varieties with gene donor varieties. The analysis was carried out by such methods as DNA extraction using the “DNA-Extran-3” commercial kit (Sintol, Russia), classical PCR with the specialized diagnostic marker Sub1A203, separation of amplicons by electrophoresis in 2 % agarose gels, analysis of electrophoregrams in the software Bio-Rad ImageLab 6.0.1. As a result of the analysis, there was identified the allelic state of the Sub1A gene in 90 rice samples. A significant number of samples carried a non-functional recessive allele, the presence of the gene was not established in 19 samples. The Sub1A gene was in the heterozygous state in 9 samples. The presence of a functional dominant allele of the target gene was identified n 5 breeding samples. There has been recommended to use these samples in breeding work aimed at developing new rice varieties resistant to prolonged flooding.

In the Rostov region, among cereal crops, winter wheat occupies a leading position in terms of the sown area. Breeders have developed wheat varieties, a productivity potential of which is 1.5–2 times higher than their actual yield in production. One of the most important factors that can destabilize gross grain harvests and reduce productivity are parasitic organisms, the most dangerous of which are rust pathogens (Puccinia triticina, P.striiformis, P.graminis). Brown rust (pathogen Puccinia triticina Erikss.) is one of the dangerous wheat diseases. The genetic diversity of cultivated varieties according to resistance types and genes that control it, provides reliable wheat protection against this pathogen. The purpose of the current study was to identify leaf rust resistance genes (Lr-genes) using marker selection for the winter bread wheat lines. The study was carried out in 2020–2021. The objects of research were 311 winter bread wheat lines of the FSBSI Agricultural Research Center «Donskoy». In the study of winter bread wheat lines, there were used such methods as DNA isolation using CTAB, PCR, and electrophoresis on agarose gels. Using molecular markers, there have been identified 24 samples with a functional allele of the Lr10 gene (1672, 518/21 (1), 595/21 (1) 595 (4), 625/21, 626/21, etc.), 49 samples with the dominant allele Lr26 (1105, 502/21, 526/21 (1), 526/21 (2), 529/21 (12), 557/21, etc.), 13 lines with the resistance allele of the Lr37 gene (1105, 1609, 1610, 1611, 1612, 1613, 1615, etc.). There was also found that the Lr17a gene was not detected in the studied lines.

Rice is one of the most widespread and cultivated crops in the world. It is necessary to increase the yield of crops or expand their sown areas to resolve a food security problem in Russia. Current impossibility of expanding rice cultivated areas in the Rostov region and the need to maintain and increase its yield require developing new disease-resistant varieties. Rice genotypes with multiple blast resistance genes avoid significant yield losses. Since pyramiding and selection of resistance genes in the same genotype through traditional selection methods are complicated, it is urgent to search for homozygous samples using marker-assisted selection methods. This study was aimed to identify Pi-1, Pi-2, Pi-33 and Pi-ta blast resistance genes in breeding rice samples by MAS-methods. The study used CTAB-method for DNA-isolation, PCR, electrophoresis on agarose and polyacrylamide gels. The resulting gels were stained in a solution of ethidium bromide and photographed in ultraviolet light. To control the presence of blast resistance genes the following parental cultivars were used: C104LAC for the Pi-1 and Pi-33 genes, C101-A-51 for the Pi-2 gene, IR36 for the Pi-ta gene; Novator and Boyarin as controls of non-functional alleles of all studied genes. The 446 selection samples of the seventh generation were analyzed. As a result of the research, 127 rice samples that combine 2 or 3 different blast resistance genes were identified. The Pi-2 and Pi-33 genes combination was identified in 43 samples (1128/1, 1149/3, 1171/2, 1177/3, 1177/4, 1186/4, et al.). Samples with three resistance genes are the most interesting for selection and further breeding. For developing new blast-resistant varieties, we recommend using rice samples with the following combinations of resistance genes Pi-1+Pi-2+Pi-33 (1197/1, 1226/2, 1271/1, 1272/2), Pi-1+Pi-2+Pi-ta (1197/4, 1304/2, 1304/3, 1482/3, 1482/4, 1486/1) and Pi-2+Pi-33+Pi-ta (1064/1, 1064/3, 1281/2, 1281/3, 1281/4, 1282/2, 1283/1, 1283/2, 1284/3).