Forage annual and perennial grasses are the difficult subject for molecular and genetic studies because of the problem with obtaining qualitative genomic DNA for PCR, due of high content of proteins, polysaccharides and polyphenols. The known methods of DNA extraction or the numerous commercial kits allow isolating purified nucleic acids from the leaf tissue, but characterized by low efficiency at seedlings using. The modified method of DNA isolation, based on the SDS-extraction buffer (sodium dodecil sulfate), is presented in this study. Significant modifications were introduced in the reagents compound and the steps of procedure accordingly to used type of plant tissue and the result was positive at usage on the bulking samples, as well as on the individual genotypes (the only seedling). Reliability of this method and the functionality of the obtained DNA samples were tested in PCR with different molecular markers (SSR, SRAP and PawS) in researches on revealing of forage legume grasses DNA polymorphism. The general advantages of the proposed method are simplicity and effectiveness, the possibility to isolate qualitative DNA without toxic reagents application, as well as relatively low cost and availability of reagents. This method can be useful for studying the genetic biodiversity and for decision the different tasks, required the rapid analysis of large plant populations.

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Rapeseed (Brassica napus L.) and turnip rape (B. rapa L. subsp. campestris (L.)) are important agricultural plants widely used for food, fodder and technical purposes and as green manure. Over the past decades, a large number of perspective varieties that are being currently cultivated in every region of Russia have been developed. To increase the breeding efficiency and facilitate the seed production, modern molecular-genetic techniques should be introduced as means to estimate species and varietal diversity. The objective of the presented research study was to investigate DNA polymorphism of the rapeseed and turnip rape varieties developed at Federal Williams Research Center of Forage Production and Agroecology and detect informative markers for varietal identification and genetic certification. To genotype 18 gDNA samples, 42 and 25 combinations of respective SSR and SRAP primers were used. The results obtained demonstrate that SRAP markers were more effective for polymorphism analysis: 36 % of the tested markers revealed genetic polymorphism compared with only 16.7 % of microsatellite loci. Molecular markers to detect differences at interspecific and intervarietal levels have also been found. For the investigated set, such microsatellite loci as Na12A02, Ni2C12, Ni02-D08a, Ra02-E01, Ni03H07а and SRAP-marker combinations as F13-R9, Me4-R7, F11-Em2, F10-R7, F9-Em2 and F9-R8 proved to be informative. Application of the two marker techniques made it possible to detect a higher level of DNA polymorphism in plants of different types (spring and winter varieties) if compared against the intervarietal differences within a species or a group. According to Nei’s genetic diversity index, in the cluster of winter rapeseed, VIK 2 and Gorizont varieties had the longest genetic distance, and in the spring cluster, these were Novosel and Veles. A high level of similarity was found between Vikros and Bizon winter rapeseed varieties. The results obtained have a high practical value for varietal specification of seed material and genetic certification of rapeseed and turnip rape varieties.