Resistance to Fusarium oxysporum f.sp. melonis race 2 is conferred by a single dominant gene, Fom-1 in melon. Here, we identiWed DNA markers tightly linked to Fom-1 that could be used for marker assisted selection in breeding programs. First, we developed 125 F 2 plants derived from the cross between melon lines P11 (fom-1fom-1) and MR-1 (Fom-1Fom-1). Using the F 2 population, we constructed a linkage map including 14 SSR markers which had not been mapped previously. Fom-1 was conWrmed to be allocated to linkage group 7. Then, we identiWed four AFLP markers using bulked segregant analysis. The AFLP marker TAG/GCC-470 was completely linked to Fom-1 and other three markers were mapped near Fom-1. TAG/GCC-470 and TCG/GGT-400 were respectively converted to STS and CAPS markers. Usefulness of DNA markers was conWrmed in the analysis with several melon cultivars and lines.

Ninety-nine accessions of melon (Cucumis melo L.) mainly from East and South Asia were analyzed based on the polymorphism of 210 amplified fragment length polymorphism (AFLP) bands to reveal the genetic structure and phylogenetic relationship in Asian melon. A cluster analysis based on their genetic similarity revealed three major clusters, i.e., a vars. makuwa and conomon group, a small-seed type group and a group of Japanese F 1 cultivars and large-seed type accessions. Most of the East Asian melon accessions classified into the first group were of the small-seed type with a seed length shorter than 9.0 mm. The varieties of C. melo were roughly divided into two groups by a principal co-ordinate analysis based on AFLP data, that is, the group of vars. makuwa and conomon and small-seed type melon and the group of var. reticulatus and large-seed type melon. Indian melon accessions were rich in genetic variation. Melon accessions closely related to vars. makuwa and conomon were found in east India, and they were considered as possible candidates of the prototype of vars. makuwa and conomon.

So far, only five microsatellite markers have been developed in common buckwheat (Fagopyrum esculentum). The purpose of the present study was to develop a larger number of microsatellite markers in common buckwheat. By sequencing 2785 clones from the libraries, which were enriched for (CT) n and (GT) n repeats using magnetic particles, it was shown that 1483 clones contained microsatellites, of which 352 had unique sequences. Primer pairs were designed for 237 of the microsatellite loci, of which 180 primer pairs each amplified PCR products. Fifty-four primer pairs that each amplified a clear PCR product of the expected size were evaluated for their ability to detect variations in common buckwheat populations and to be utilized in seven related Fagopyrum species. Forty-eight (88.9%) out of the 54 microsatellite markers tested were found to be highly variable (the average number of alleles was 12.2 and the average polymorphism information content (PIC) was 0.79) in a population of cultivated buckwheat. This PIC value was comparatively large when compared with the average values for microsatellite markers reported for other crops. A high rate of successful amplification of common buckwheat microsatellite markers was observed in closely related species; in particular all the 54 loci were successfully amplified in the wild ancestor of cultivated common buckwheat. The microsatellite markers developed in the present study should contribute to the promotion of molecular breeding in common buckwheat.

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