GENOMIC VARIATION AND RELATIONSHIPS IN AERIAL YAM (DIOSCOREA-BULBIFERA L) DETECTED BY RANDOM AMPLIFIED POLYMORPHIC DNA

Random amplified polymorphic DNA (RAPD) markers were used to assess in traspecific variability and relationships in aerial yam (Dioscorea bul bifera L.). A total of 23 accessions from different geographic locatio ns in Africa, Asia, and Polynesia were analyzed by 10 arbitrarily chos en GC-rich decamer primers. Using cesium chloride purified genomic tem plate DNA, highly reproducible polymorphic fingerprints were generated by all 10 primers, resulting in a total of 375 informative characters . Only eight bands were monomorphic among all investigated accessions. A binary character matrix was generated by scoring for presence/absen ce of a band at a particular position, transformed into a matrix of pa irwise distances using either the Jaccard or a simple matching coeffic ient, and analyzed by neighbour joining, UPGMA (unweighted pair group method with arithmetic averaging) cluster analysis, or split decomposi tion. All methods of data evaluation resulted in similar groupings tha t reflected the geographical origin of the samples. The African access ions formed a distinct isolated group, whereas Asian and Polynesian ac cessions proved to be more heterogeneous. With two exceptions (var. su avior and var. sativa), the RAPD data supported previous varietal clas sification based on morphological characters. Stepwise reduction of th e number of evaluated characters did not affect branching patterns of the trees above a minimum threshold of 150.