RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) MARKERS FOR GENETIC-ANALYSIS IN ALLIUM

RAPD analysis was applied to onion (Allium) cepa) and other Allium spe cies in order to assess the degree of polymorphism within the genus an d to investigate if this approach was suitable for genetic studies of onion. Seven cultivars of A. cepa, including shallot, and single culti vars of Japanese bunching onion (A. fistulosum), chive (A. schoenopras um), leek (A. ampeloprasum), and a wild relative of onion (A. roylei), were evaluated for variability using a set of 20 random 10-mer primer s. Seven out of the twenty primers revealed scorable polymorphisms bet ween cultivars of A. cepa and these will be further evaluated for use in genetic mapping. Wide variations in banding profiles between specie s were observed with nearly every primer tested. These were assessed f or use in systematic studies within the genus. Ninety-one band positio ns were scored (+ / -) for all the cultivars studied. Genetic distance s between each of the cultivars were calculated and cluster analysis w as used to generate a dendrogram showing phylogenetic relationships be tween them. The resulting analysis was in broad agreement with previou s classifications of the species studied, confirming the validity of t he method. However, amongst the species studied, it placed A. roylei a s the closest relative of A. cepa, questioning the current classificat ion of the former species in the section Rhizideum.