Development of 101 novel SSR markers and construction of an SSR-based genetic linkage map in cucumber (Cucumis sativus L.)

Cucumber (Cucumis sativus L.) is an important vegetable crop grown worldwide, but the number of available and mapped simple-sequence repeat (SSR) markers is insufficient for construction of an SSR-based genetic linkage map. To improve this situation, we developed SSR markers from SSR-enriched genomic libraries for C. sativus. We sequenced 2304 clones, and obtained 101 primer pairs which showed clear amplification and polymorphism among genotypes in either C. sativus or Cucumis melo (melon). In C. sativus, all were amplified and 91 were polymorphic among the three genotypes that we analyzed. In C. melo, 41 were polymorphic among the three genotypes that we analyzed, but 32 were not amplified. In addition to the SSRs developed in this study, we used SSRs and sequence-characterized amplified regions (SCARs) reported previously in cucumber and melon to construct the first SSR-based linkage map of cucumber. The map now comprises 120 SSRs and 6 SCARs. It contains 22 markers from previous cucumber maps and 8 linkage groups, and spans a distance of 625.7 cM. The present map is the most comprehensive one in terms of the number of SSR markers and will therefore be highly useful in future cucumber genetic studies.