ELKE FISCHER, TANJA BERNDL, RAINER SCHULTZE-KRAFT
University of Hohenheim, Institute of Plant Production and Agroecology in the Tropics and Subtropics, Department of Biodiversity and Land Rehabilitation, Germany
``Desmodium ovalifolium'' is the abbreviated and most commonly used name for the taxonomically valid name Desmodium heterocarpon L. DC. subsp. ovalifolium (PRAIN) OHASHI. This species originates from Southeast Asia, namely Thailand, Cambodia, Laos, Vietnam, Malaysia, Indonesia and the Philippines. Since it is well-adapted to the acid, low-fertility soils of the humid tropics and has low nutrient requirements, D. ovalifolium has a high potential to be used as multi-purpose legume (e.g. soil cover, forage) in tropical production systems. The actual world collection of D. ovalifolium accessions is maintained in the CIAT genebank and basic passport data are available. However, little is known about the genetic structure of this collection. Therefore, as an initial step the random amplified polymorphic DNA (RAPD) technique was adjusted for D. ovalifolium and a total of 100 primers was tested. Twelve of these decamer primers were informative and yielded 18 polymorphic fragments. Based on the obtained data, Jaccard similarity (JS) coefficients were calculated for 146 accessions and a dendrogram was generated by means of the unweighted pair group method (UPGMA). Analysis of the clusters showed no correlation between ecogeographic origin and grouping of the accessions. Besides, a large number of accessions showed identical banding patterns leading to the assumption that some of them are probably duplicates of the same genetic material. In order to provide a structured sample from the collection and to reduce the number of accessions to a more manageable size for further research, the maximisation strategy was used for generating a tentative core collection consisting of 20 accessions. The combination of these accessions maximises the number of observed alleles at the marker loci in the core while keeping the total number of accessions to a specific limit and ensuring a minimum number from every group.
Keywords: Core collection, Desmodium ovalifolium, RAPD