Stidies On Genetic Relationships And Cultivar Lderntification In Watermelon(Citrullus Lanatus(Thumb.)Masf.)Using Molecular Markers Technique

RAPD(Random Amplified Polymorphic DNA) and SSR(Simple Sequence Repeat) were employed in order to study the genetic relationships of 32 watermelon (Cit rullus Ianatus (Thunb.) Masf.) germplasm, the purity and authenticity of hybrid 搄ingxin No.1攖hat was cultivated most in Beijing. We established rudimentally the techniqe of molecular marker 梐ssisted-selection for purity test and authenticity identification of seed in quantity. The main results were obtained as follows: 1. RAPD analysis was applied to assess the genetic relationships among 32 accessions of watermelon (Citrul/us Ianatus (Thunb.) Mans f). 15 primers (2.08%) were screened from 720 arbitrary 10-mer primers, and a total of 104 DNA bands were amplified,43 of which (41.35%) were polymorphic. The average number of DNA band amplified by each primer was 7.0. A tree diagram was constructed by using complete linkage method. The 32 cultivars were assigned to 6 groups which were East-Asia group, American group, 2 medial groups and 2 Africa wild groups. Each ecological type group has its specific bands which were available to discriminate other groups and we also study the genetic relationships of different cultivars of each ecological type group. The results obtained by RAPD are fundamentally identical with their origins and characteristics and the genetic diversity in watermelon was narrow. SSR was used to study basically the genetic relationships among 32 accessions of watermelon (Citrullus Ianatus (Thunb.) Mansf). The result was that abundant SSR polymorphism between wild types and cultivars, few polymorphism among cultivars. 2 2. We found two RAPD markers named QPPO1/570bp and OPM16/390bp that could be used to detect the purity and authenticity of hybrid 搄ingxin No.1? RAPD marker QPPO1/570bp was transferred into a SCAR marker SCPO1/570bp that was only applied on purity test. RAPD marker OPMI6/390bp could be used on purity test and authenticity identification, but it was difficult to be transferred into a SCAR marker. We testify the purity of hybrid 搄ingxin No.1攚ith SCAR marker SCPO1/570bp and RAPD marker OPPO1/390bp. The results were proved . It was available and accurate to identify the purity and authenticity of hybrid with molecular markers technique.