The genetic diversity of melon market types (Cucumis melo L., 2n = 2x = 24) in China, an important secondary center of diversity, has not been examined. Therefore, reference accessions from India and Africa, Crete/Greece, Japan, Europe, U.S.A., Spain, and 68 Chinese cultigens (fresh-market nonnetted thin-skinned; non-netted thick-skinned; netted thick-skinned; and non-netted thin-skinned, and vegetable) were evaluated by using 17 10-mer RAPD primers (32 mapped loci), days to Xower, sex expression, lateral-branch number, and fruit number and weight per plant. While Chinese thin-skinned melons diVered from vegetable melon types only in sex expression, the U.S. Western Shipping market type reference accession "Top Mark" and Chinese thickskinned melons were similar for all of the morphological traits examined. The average similarity (Jaccard CoeYcient) between any two pairs of accessions examined as estimated by RAPD variation was 0.47 § 0.14. Within-group genetic similarities ranged between 0.94 (thin-skinned type) and 0.08 (nonnetted thick-skinned type). The average/standard deviation, maximum, and minimum similarity between any two Chinese reference accessions was 0.41 § 0.13, 0.75, and 0.12, respectively. Cluster analysis partitioned accessions into two main branches consisting of Group Cantalupensis and Inodorus reference accessions (clade 1) and Chinese accessions (clade 2). A second cluster analysis partitioned China, India, and Africa accessions into one major group, and accessions from Japan, Europe, and U.S.A. into another. Results indicate that Chinese accessions are a rich source of genetic diversity for plant improvement, and that molecular assessments support previously described theoretical melon domestication patterns constructed from historical and archeological evidence. KeywordsGenetic similarity · Morphological traits · Multivariate analysis · RAPD Abbreviations THIN Fresh-market, non-netted, thin-skinned melon THICK Non-netted, thick-skinned melon NET Netted, thick-skinned melon VM Non-netted, thin-skinned, vegetable melon DF Days to 50% Xower LBN Lateral-branch number on main stem FN Fruit number per plant FW Fruit weight per plant

Beit Alpha cucumber (Cucumis sativus L.) is a Mediterranean fresh-market type with a relatively narrow genetic base. To broaden its base for plant improvement, 42 diverse accessions were compared employing a previously defined standard marker array to choose wide-based parental lines for use in backcross introgression. Inbred backcross lines (IBL) were developed by crossing Beit Alpha line '04HD5' (De Ruiter Seeds, The Netherlands; recurrent parent) and PI 285606 (Poland; donor parent), and then selecting the most genetically diverse BC 1 and BC 2 progeny based on molecular marker profiles, followed by three generations of single-seed descent to produce 117 IBL. Molecular genotyping of IBL was then performed, and IBL were evaluated for days to anthesis, sex expression, pistillate flowers per node, lateral branch number, fruits per plant, fruit length, and fruit weight in the US, The Netherlands, Israel, and Turkey. Multivariate analyses and genetic distance comparisons indicate that IBL possessed considerable inter-line morphological and genotypic diversity. These diverse IBL will be useful in genetic studies and to evaluate Beit Alpha cross-progeny derived from IBL 9 elite germplasm created to broadened genetic base of this market type.