MICROSATELLITE LOCI POLYMORPHISM IN RUSSIAN BLACK CURRANT ( <i>Ribes nigrum</i> L.) VARIETIES FROM COLLECTION OF ALL-RUSSIAN RESEARCH INSTITUTE OF BREEDING FRUIT CROPS
Black currant is the main berry crop in Russia. The need to improve its assortment requires new effective methods to be involved in breeding. Application of DNA markers as a modern approach in dealing with germplazm is intensively used abroad in works on black currant plants. We are the first in Russia who used SSR DNA markers in studying black currant gene pool. In this paper we report genotyping 27 black currant accessions from the collection of the All-Russian Research Institute of Breeding Fruit Crops, including 16 varieties originated from this institute, on 14 microsatellite loci. Electrophoresis in 6 % denaturing PAAG followed by staining with silver nitrate was used for separation of PCR products. All tested SSR loci, except MS06g03, have been found to be polymorphic. On average 4.9 alleles were amplified per locus. Three fragments have been amplified on DNA of some accessions at one SSR locus that is probably due to the duplication of these microsatellite loci in genome of these accessions. A total of 66 % of all amplified fragments were rare alleles with a frequency of occurrence equal to or less than 0.2. Eight unique alleles have been found. The observed heterozygosity ranged from 0.259 (g2-H21) to 1 (e4-D03) and averaged 0.608. Combinations of alleles at one locus allowed to distinguish from 3 (g2-H21, e1-O21) to 15 (g2-G12) genotypes. The minimum set of four loci (e4-D03, g1-M07, g1-E03, g2-B20) allowed to distinguish all the tested accessions, i.e. unique multilocus profile has been found for each sample. Pairwise genetic similarity coefficients ranged from 0.11 (between Odzhebin and Sharovidnaya varieties) to 0.95 (between Govtva and Rtishchevskaya varieties) and averaged 0.346. Cluster analysis of genetic similarity has been done. The dendrogram shows a few clusters with high bootstrap support. Distribution of alleles between related varieties was consistent with the pedigrees in the most cases, but discrepancies between pedigrees and SSR data also were found. Thus, the varieties Ocharovanie (¹ 1168 ½ Ekzotika variety) and Ekzotika had no common alleles in three loci (e4-D03, g1-E03, g2-B20). It probably is due to pollination by other pollen or error in reproduction and transplantation or mutations in these loci. The varieties Odzhebin and Binar (Odzhebin х Naryadnaya) had no common alleles in two loci (g1-M07, g1-E03). Our results allow to recommend SSR markers for evaluation of domestic gene pool of black currant on genetic diversity, and to develop methods for the identification and certification of varieties of black currant.