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Rice is a valuable crop used for food throughout the world. To develop modern, productive and disease resistant rice varieties, it is necessary to accelerate the breeding process using molecular biology methods. The purpose of the current study was to identify alleles of six blast resistance genes (Pi-1, Pi-2, Pi-33, Pi-40, Pi-ta and Pi-b) in the selected rice samples using MAS (marker-associated selection method). The objects of the study were 446 breeding rice samples sent to the laboratory of cell breeding for analysis by breeders from the laboratory for rice breeding and seed production of the FSBSI «ARC «Donskoy». Identification of genes in them was carried out differentially and was determined by the pedigree of the samples. In order to determine the alleles of the blast resistance genes Pi-1, Pi-2 and Pi-33, all 446 samples were studied, for the Pi-40 gene there were studied 20 samples, for the Pi-ta gene there were studied 316 samples. For DNA extraction, there was used a Russian-made kit ‘DNA-Extran-3’. PCR was performed using specific primers of the target genes. Identification of reaction products was performed on agarosegels after photographing in ultraviolet light. As a result of the study, there were identified the rice samples which carried from 1 to 5 blast resistance genes in various combinations. There have been identified 14 samples that possess a set of 5 resistance genes, such as 2723, 2724, 2727, 2728, 2729, 2730, 2733, 2735, 2736, 5007, 5671, 5673, 5450/2 and 2450/2. The information obtained from the results of the study could then be used by breeders to use valuable genotypes as donors in crosses, as well as to select promising breeding material resistant to blast disease.

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).

Blast resistance genes of rice and their markers (review) Rice blast is a very harmful and dangerous disease, caused by the fungus pathogen Pyricularia oryzae Cavara риса (Oryza sativa L.). The use of the varieties resistant to the disease is one of the efficient ways to protect plants from diseases. The recent progress in rice genomics allowed using DNA-markers to grow resistant varieties through marker breeding (MAS). The article summarizes the information about blast resistance genes of rice and their markers, which can be used in breeding. The article gives the data about registered genes and their number, chromosome loci, regularities of stability, samples-donors and molecule characteristics of cloned genes. Besides, several questions about a nomenclature system and identification of resistance genes have been considered in the paper. The information can help rice breeders improve rice blast resistance through marker breeding. ARRIGC together with ARRI of rice and SFU have started breeding rice varieties resistant to blast through marker breeding since 2003. Their long-term work in the introgression of resistance genes by PCR-analysis resulted in the development of the rice variety ‘Magnat’ with the genes Pi-1 and Pi-2, and in 2015 there were obtained pyramid rice lines with five rice blast resistance genes Pi-l, Pi-2, Pi-33, Pi-ta and Pi-b.