ARS | Publication request: Genetic Diversity of Spanish Melons (Cucumis melo L.) of the Madrid Provenance

Submitted to: Cucurbitaceae Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 30, 2008
Publication Date: September 15, 2008
Citation: Escribano, S., Lazaro, A., Staub, J.E. 2008. Genetic Diversity of Spanish Melons (Cucumis melo L.) of the Madrid Provenance. Cucurbitaceae Proceedings.

Interpretive Summary: It is important to obtain genetic diversity (how genetically different plants are from different parts of the world) in order to determine which plants might be most useful in a plant breeding program. Genetically diverse plants have greater potential for resisting plant pathogens (fungi, bacteria and viruses) that decrease yield and quality. If plants can be identifed from foreign sources which have potential for breeding, then future cultivars will be more diverse genetically. Spain is a diverse center for melon since there are many melon forms unlike those found in the U.S. Agricultural production of melon in Spain is ~ 1.1 mil tons/year (2005), of which ~6% are harvested in the Madrid provenance where it is the most important crop species. A small village named Villaconejos exists about 50 km south of Madrid. It has achieved national prominence for its unique landrace cultivars (plants that naturally inhabit agricultural areas as opposed to introduced cultivars) which originated in the nineteen century. Their special organoleptic attributes (i.e., taste, juiciness, and sweetness) initially received local consumer acceptance, and then national notoriety, where "Villaconejos melons" continue to be synonymous with exceptional culinary quality. These melon types might be useful for U.S. agriculture. A multidisciplinary approach was initiated to provide a comparative assessment of Villaconejos melon diversity and fruit quality, and to determine if these landraces differ from among themselves, from other Spanish melon types, and from U.S. types. It was determined that the examined from Villaconejos were very different from other Spanish and U.S. melons. Thus, they might have potential for increasing the genetic diversity of U.S. melon types. This information can be used directly by public and private U.S. melon breeders to transfer the genetic diversity from Villaconejos to U.S. types through traditional plant breeding techniques. Such transfer of genetic diversity will improve the global competitiveness of U.S. melon growers.

Technical Abstract: The genetic diversity of five Group Inodorus landraces having a historic presence in the town of Villaconejos, Spain (near Madrid) and four reference accessions (one accession Group Flexuosus) (Lopez-Sese et al, 2002), was assessed using the allelic variation at 19 SSR loci. Seventy-two polymorphic bands were scored which provided for adequate discrimination among the accessions examined. Cluster analysis (UPGMA) employing SSR-based genetic similarity (GS, Jaccard similarity coefficient) data resulted in a dendrogram with two major clades. Although Group Inodorus accessions were represented in both clades, genetic differences among two Madrid accessions and the other seven landraces were remarkable. In fact, this genetic difference (GS = 0.24; lack of genetic affinity) was lower than the difference between the accession C-444 and the other Inodorus landraces accessions examined (GS = 0.25). Moreover, the high level of heterogeneity observed within the accessions indicates that the melons examined possess broad genetic diversity. These results suggest that an expanded genetic analysis of traditional landraces of the Madrid provenance would be warranted to assess their potential utility for plant improvement.