Genetic diversity in melon (Cucumis melo L.): Anevaluation of African germplasm

The genetic diversity among 126 exotic (108) andreference array (RA) melon (Cucumismelo L.) accessions (18) was assessed byvariation at 49 random amplified polymorphic DNA marker bands(putative loci) using 29 10-mer primers. Africanaccessions of unknown melon market classes were compared to the RAaccessions from a broad range of C.melo subsp. melo groups(Cantalupensis, Conomon, Inodorus and Flexuosus). Althoughdifferences in groupings occurred after multidimensional scaling andcluster analysis, both analyses placed African accessions into twogroups, which were separate from RA groupings. One African group of33 accessions containing accessions from Zimbabwe (5),Zambia (24), Mali (1), one of two Senegalaccessions and two of three South African accessions examined. Thesecond group, which consisted of 67 accessions containing collectionsfrom Egypt (40), Tunisia (6), Libya(13), Morocco (1), Algeria (2),Ethiopia (1), Niger (1), Sierra Leone(1), S. Africa (1), Zambia (1) andZimbabwe (1). Depending on the multivariate analysistechnique employed, accessions from Kenya, Senegal and Ghana formedeither unique groupings or were grouped with accessions(Cantalupensis) from the RA. Both analyses indicate thatthe genetic differences inherent between the African gene pools isassociated with the geographic proximity of African countries(northern vs. central-southern Africa) in thegermplasm array examined. Moreover, these data indicate that thegenetic diversity of U.S. and European commercial RA germplasm(Cantalupensis and Inodorus) could be enhanced by theintroduction of genetic variation from African accessions, and thatit would be advantageous to acquire more accessions from thisgeographically and ecologically varied region to ensure the retentionof existing genetic diversity.