Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2003
Publication Date: 8/20/2003
Citation: Staub, J.E., Fanourakis, N., Lopez-Sese, A.I. 2003. Genetic diversity in melon (Cucumis melo L.) landraces from the island of Crete as assessed by random amplified polymorphic DNA and simple sequence markers. Euphytica. 136:151-166. Interpretive Summary: Plant species differ genetically for visual (phenotype) and cellular (pertaining to the cell) traits. Fruit yield and fruit quality are examples of phenotypic traits. The analysis of DNA (contained in the cell) of organisms is now used to determine differences between plants. The biotechnological tool associated with the analysis of DNA is called molecular marker analysis. Molecular markers are segments of DNA used to identify differences in DNA between organisms. Melon varieties differ in their plant habit (stature as small or large) and their DNA. Although Greek melons differ in phenotype from U.S. melon types, the extent of differences in their DNA is not known. In contrast to U.S. melon varieties that are uniform (hybrids), many Greek melons are not uniform and are referred to as landraces (mainly grown on Crete and other smaller islands of Greece). There are many attributes in Greek landraces that might be used to improve U.S. melon (e.g., pest and disease resistance, fruit quality, and long self life). However, in order for U.S. public and private plant breeders to utilize Greek landraces in their plant improvement programs, the phenotype and DNA variation (differences) among these landraces must be characterized and compared to the U.S. melon types. Therefore, an experiment was designed and executed to determine the phenotype and DNA variation among Greek melon landraces and commercial varieties (i.e., uniform lines and hybrids). The data indicate that U.S. and Greek melon are very different in both phenotype and DNA. The data also provide the plant breeder with working strategies for the incorporation of genes from Greek landraces into U.S. melon types. This will allow the plant breeder to work more efficiently and effectively, and thus shortened the time to develop improved melon varieties for U.S. consumption. Improved melon varieties will in turn make the U.S. grower more competitive while providing an unique product to the U.S. consumer.
Technical Abstract: Diversity among 17 melon (Cucumis melo L.) Group Cantalupensis, Inodorus, and Flexuosus varieties (landraces and inbred lines) from Greece was assessed using 24 10-mer RAPD primers (65 loci), 11 morphological fruit traits, two yield-rated characteristics, and resistance to powdery mildew infection [Sphaerotheca fuliginea (Schl. Ex Fr.) Poll.]. Accessions were genetically diverse (average genetic distance among accessions = 0.46 0.19), where the greatest variation was detected among Group Flexuosus. Comparative analysis of Greek varieties and an array of previously characterized reference accessions (68 from Africa, Central Europe, Japan, and Spain) spanning major market classes employing 19 RAPD primers (34 loci) indicates that all but one of the varieties from Greece showed genetic affinities among themselves and 23 accessions of varying origin (i.e., Japan, Central Europe, Spain, and Israel) and market class. Accessions from Greece were, however, distinctly from the African landraces and most of Spanish melons. Greek accessions also showed little genetic affinity with the Casabas (Blanco and Crenshaw), Ogen, and U.S. Eastern Market accessions. Data indicate that Group Flexuosus and Inodorus accessions from Greece have genetic affinities with Western Asian and Mediterranean market classes, respectively. The proximity of Greece and more specifically Crete to ancient trade routes might partially explain the genetic relationships detected, affording doors of commercial opportunity and consequently avenues for gene exchange. The uniqueness of Greek melon landraces portends their potential usefulness for the enhancement of U.S., European, and Asian melon market classes.