ARS | Publication request: GENETIC DIVERSITY IN MELON (CUCUMIS MELO L): AN EVALUATION OF AFRICAN GERMPLASM

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 2000
Publication Date: N/A

Interpretive Summary: The preservation of biological diversity (differences among plants and animals) is critical for sustaining population growth and enhancing global nutrition. The types and distribution of plants and animals can be changed by the careless use of renewable (e.g., forest) and nonrenewable rescues (e.g., land). It has become clear that threats to biological diversity are increasing. This is primarily due to the increased tempo of utilization and population pressure on cultivable land. Efforts to sustain population demands on agriculture productivity will necessitate an increase in the effective use of germplasm during plant improvement. Melon is an economically important crop which originates from Africa. It is important to identify African sources of genetic diversity from which man can draw for the improvement of this crop. The extent of genetic diversity in African melon has not been studied. Therefore, we designed studies which looked at the DNA (the genetic code in cells) to determine the extent of genetic diversity in African melon. We determined that Africa is a rich reservoir of genetic diversity and that plant breeders could use this diversity to improve commercial melon. Data supplied with our study can be used by agriculturists to create plans for more efficient utilization of this crop and to plan for further collections of wild melons (landraces) from Africa.

Technical Abstract: The genetic diversity among 125 exotic (108) and reference array (RA) melon (Cucumis melo L.) accessions (18) was assessed by variation at 49 random amplified polymorphic DNA marker loci using 29 10-mer primers. African accessions of unknown melon market class were compared to RA accessions from a broad range of C. melo subsp. Melo groupins (Cantalupensis, Conomon, Inodorus, and Flexuosus). Although differences in synthetic groupings occurred after multidimensional scaling and cluster analysis, both analyses identified African accessions in two groups, distinctly separate from RA groupings. First group consisted of 33 accessions. All accessions from Zimbabwe, Zambia, Mali, one of two Senegal accessions, and two to three South African accessions examined. The second group consisted of 67 accessions containing, with rare exception, all accessions from Egypt, Tunisia, Libya, Morocco, Algeria, Ethiopia, Niger, Serra Leone, S. Africa, Zambia, and Zimbabwe. Both analyses indicate that the genetic differences inherent between the African gene pools is associated with the geographic proximity of African countries (northern vs. central-southern Africa) in the germplasm array examined. Data indicated that the genetic diversity of U.S. and European commercial RA germplasm (Cantalupensis and Inodorus) could be significantly enhanced by the introduction of genetic variation from African accessions, and that it would be advantageous to acquire more accessions from this geographically and ecologically varied region to ensure the retention of existing genetic diversity.