VARIATION IN RANDOMLY AMPLIFIED DNA MARKERS AND STORAGE ROOT YIELD INJEWEL SWEET-POTATO CLONES

Polymorphism analysis and yield tests were conducted among 'Jewel' swe etpotato clones [Ipomoea batatas (L.) Lam] obtained from eight state f oundation seed programs. Initially, 38 arbitrary primers generated a t otal of 110 scorable DNA fragments in a sample of virus-indexed plants from each clone source. The number of marker loci scored for each pri mer varied from one to eight with an average of 2.89. Twenty-one bands (19.1%) were scored as putative polymorphic markers based on the pres ence or absence of amplified products. Further estimation of variabili ty within each clone source was accomplished by an assay of 10 sample plants per clone group by 14 marker loci generated by four selected pr imers. Polymorphic bands ranged from 7.1% to 35.7% in five of eight cl one groups, Field studies show variation in nearly all yield grades me asured. In three tests during the 1991 and 1992 seasons, yield differe nces ranged from 27% to 46% within the economically important U.S. no. 1 root grade. The results suggest the usefulness of arbitrarily-prime d markers in detecting intra-clonal sweetpotato DNA polymorphisms and indicate an underlying genetic cause for phenotypic variability in the crop.