Length polymorphism and homologies of microsatellites in several Cucurbitaceae species

The objectives of this research were to assess (1) the degree of Simple Sequence Repeats (SSR) DNA length polymorphism in melon (Cucumis melo L.) and other species within the Cucurbitaceae family and (2) the possibility of utilizing SSRs flanking primers from single species to other genera or species of Cucurbitaceae. Five melon (CT/GA) _n SSRs were isolated from a genomic library. Two cucumber (Cucumis sativus L.) SSRs were detected through a search of DNA sequence databases, one contained a (CT)₈ repeat, the other a (AT)₁₃ repeat. The seven SSRs were used to test a diverse sample of Cucurbitaceae, including 8 melon, 11 cucumber, 5 squash, 1 pumpkin, and 3 watermelon genotypes. Five of the seven SSRs detected length polymorphism among the 8 melon genotypes. PCR amplification revealed between three and five length variants (alleles) for each SSR locus, with gene diversity values ranging from 0.53 to 0.75. Codominant segregation of the alleles among F₂ progeny was demonstrated for each of the five SSR loci. Four of the seven SSRs detected polymorphism among the 11 cucumber genotypes, with gene diversity values ranging between 0.18 and 0.64. Primers specific to SSRs of C. melo and C. sativus also amplified DNA extracted from genotypes belonging to other genera of the Cucurbitaceae family.