RAPD Analysis In Genetic Purity Of Cultivar 'Biyu' And Variety Identification In Cucumber (Cucumis Sativus L.)

Cucumber(Cucumis sativus L.), is one of the most popular vegetable crops grown all over the world. It has large production area and lots of cultivars, so it is easiliy to cause the cultivar mixture. At the same time, heterosis is singnificant in cucumber, and the F₁ hybrid cultivars were more and more popular in the seed market. However, at the present, most of the hybrid seeds of the cucumber are produced by hand emasculation and hand pollination. It is hard to control the seed quality, so low genetic purity seed would cause big losses. Therefore, it is of critical importance to distinguish varieties and evaluate the genetic purity of hybrid in seed production and trade.Field plot planting is a credible and exact method in cultivar identification and purity testing. 31 cucumber cultivars in the middle-lower reaches of ChangJiang River were identifed in the filed plot. Cucumber production technology in early spring was put forward in this study. Botanical and important horticultural traits of 31 main cucumber cultivars were investigated in detail, and characters were evaluated and analysed. The results would provide valuable information for the cultivar choosing and indentifying in early spring cucmber production in the east of China.The molecular marker RAPD was used to carry out germplasm identification and genetic diversity analysis of cucumber cultivars. The genetic diversity analysis of 31 cucumber varieties was studied using 13 primers with RAPD molecular marker. Total of 84 bands were observed with 52 bands shared and polymorphic ratio was 61.90ï¼…. The number of polymorphic bands generated by each primer was four on average and the average similarity coefficient in cultivars was0.90. The Cluster analysis and relatively genetic distance indicated that four clusters were obtained in the dendrogram. The result showed that none of the primes can dearly discriminate all cultivars. Cluster analysis(UPGMA) showed the cultivars share similar horticultural traits clustered at a lower genetic distance, and can reveal the relationship of the cultivars in the extent. The results would play important role in the indentification of cultivar and germplasm in cucmber. The molecular marker RAPD was used to evaluate seed purity of a commercial hybrid cucumber cultivar 'Biyu'. 44 primers were screened from 395 the ones that could be beneficial to the purity identification of cucumber hybrid seeds. The results showed that there were 15 primers of partial female type, 15 primers of partial male type, ten primers of peculiar type and ten primers of shortage type. It was found there were two false seeds and one male seed among 205 cucumber hybrid seeds when the purity of cucumber cultivar 'Biyu' hybrid seeds were identified with two primers of partial male type NAURP287, NAURP1100 and two primers of partial female type NAURP1184, NAURP120. The purity of the cucumber cultivar 'Biyu' hybrid seeds was 98.54ï¼…. The result was in well accordance with inspecting results in the field. Therefore, the molecular marker RAPD is a high efficient and reproducible way for genetic purity testing of cucumber commercial hybrid seeds.