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.

A cDNA clone encoding a putative EIN3-like protein (DC-EIL1) was obtained from total RNA isolated from senescing carnation (Dianthus caryophyllus L.) petals using RT-PCR and RACE techniques. The cDNA (2382 bp) contained an open reading frame of 1986 bp corresponding to 662 amino acids. The amino acid sequence of the N-terminal half of the protein, ranging from 80-300 amino acid residues, had 84% identity with that of the corresponding regions of Arabidopsis EIN3 and tobacco TEIL, although the overall identity was 49% and 52%, respectively. Northern blot analysis revealed that the amount of mRNA corresponding to DC-EIL1 decreased in flower tissues, especially in petals, during natural senescence and senescence induced by exogenously applied ethylene or ABA.

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Use of resistance genes would be the most effective way to address Fusarium wilt caused by Fusarium oxysporum f.sp. melonis in melon. In this study, based on the BAC 31O16 sequence which contains the cluster of melon resistance gene homologue, we developed four new DNA markers linked to Fom-1, a dominant resistance gene against F. oxysporum f.sp. melonis races 0 and 2. Linkage analysis using 125 F 2 plants derived from the cross between P11 (fom-1fom-1) and MR-1 (Fom-1Fom-1) indicated that Fom-1 was located between CAPS markers C-MRGH12 and 62-CAPS at a distance of 0.4 and 1.2 cM, respectively. Map position of Fom-1 was confirmed using another mapping population consisting of 104 recombinant inbred lines derived from the cross P11 · MR-1. The analysis of 43 fixed lines and 27 commercial F 1 hybrids showed that the developed DNA markers linked to Fom-1 correctly predicted the genotype in relation to the variety, suggesting that the region around the Fom-1 locus is very polymorphic or there is no linkage disequilibrium between the locus and the marker loci.