Development and characterization of microsatellite markers in Cucumis

This study provides a set of useful SSR markers and describes their develop ment, characterization and application for diversity studies. Sixty one Cuc umis SSR markers were developed, most of them (46) from melon (Cucumis melo L.) genomic libraries. Forty of the markers (30 melon and 10 cucumber SSRs ) were evaluated for length polymorphism in a sample of 13 melon genotypes and 11 cucumber (Cucumis sativus L.) genotypes. PCR-amplification revealed up to six size alleles among the melon genotypes and up to five alleles amo ng the cucumber genotypes, with mean gene-diversity values of 0.52 and 0.28 for melon and cucumber, respectively. These differences are in accordance with the known narrower genetic background of the cucumber. SSR data were a pplied to phylogenetic analysis among the melon and cucumber genotypes. A c lear distinction between the 'exotic' groups and the sweet cultivated group s was demonstrated in melon. In cucumber, separation between the two sub-sp ecies, C. sativus var. sativus and C.sativus var. hardwickii, was obtained. Conservation of SSR loci between melon and cucumber was proven by sequence comparisons.