THE ROLE OF BIOTECHNOLOGY Villa Gualino, Turin, Italy – 5-7 March, 2005 183 EVALUATION OF CUCUMBER ACCESSION HOMOGENITY BY USING RAPD MOLECULAR MARKERS L. Lepse*, T. Sjakste**, I. Rashal** * Pūre Horticultural Research Station, Abavas iela 2, Pūre, Tukuma raj., LV 3124, Latvia, e-mail: pures_dis@tukums.parks.lv ** Institute of Biology, University of Latvia, Miera iela 3, Salaspils, LV- 2169, Latvia; tanja@email.lubi.edu.lv; izaks@email.lubi.edu.lv Summary The method for high quality DNA isolation from the cucumber seeds was developed. Sib- and inbred lines created from the old Latvian cucumber variety 'Dindoņa Zaļie Ķekaru' were evaluated for homogeneity by RAPDs. Five lines were selected for submission in the Latvian Gene Bank of Cultivated Plants based both on molecular and field evaluation data. Keywords Cucumber, molecular markers, RAPD, homogeneity, DNA isolation Introduction Latvia is close to the northern boundary of cucumber cultivation. Therefore cucumbers of Latvian origin may contain genes of tolerance to frost and broad temperature fluctuations. Till the middle of the 1990s, PGR activities in Latvia were not conducted. Therefore evaluation of the available varieties and their entry to the gene bank became important and immediate tasks. In 1997, the Latvian Gene Bank of Cultivated Plants was established in the framework of the Nordic–Baltic cooperation in PGR [1]. Several available cucumber samples were included in the list of accessions to be preserved. The problem of accession quality was raised, as genetic erosion of some of them during commercial seed production was observed. For example, only 3% of plants of the old Latvian variety 'Dindoņa Zaļie Ķekaru' grown from commercially available seeds were morphologically corresponded to the variety description. Such material was not valuable for entry in the gene bank. Therefore homogenisation of the variety was started with the aim to select homogeneous lines that best corresponded to the original trait complex of the variety 'Dindoņa Zaļie Ķekaru', for placement in the Latvian Gene Bank of Cultivated Plants. Material and Methods Several inbred and siblines of the cucumber variety 'Dindoņa Zaļie Ķekaru' were created. For creating inbredlines, the most typical plants from commercially available seeds were chosen for selfing. During six generations, plants most corresponding to the original description of the variety by a complex of traits were selected for further inbreeding. For creating siblines, plants most corresponding to the variety were selected among plants grown from uncontrolled pollination. Next year progenies of each such plant were recognised as a sibline. Selection of the most typical plants and pollination in each following was made within siblines. Phenology, morphological parameters (plant branching, flowering type, fruit development in clusters, fruit shape, cross section of fruits and size of ovary, fruit colour, drawing, density and size of warts, colour and type of prickles) and yield were scored for six generations of inbredlines and three generations of siblines.