GENETIC SIMILARITY AMONG ECOTYPES OF ARABIDOPSIS-THALIANA ESTIMATED BY ANALYSIS OF RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISMS

Genetic similarity was estimated among a sample of 28 ecotypes of Arab idopsis thaliana. Twenty-five previously mapped genomic clones were us ed as probes in Southern hybridizations to detect restriction fragment length polymorphisms (RFLPs). A total of 62 polymorphic restriction f ragments were classified as to their presence or absence for each geno type. The genetic similarity between each pair of ecotypes was calcula ted as the ratio of concordant to total bands scored. The mean genetic similarity among the 28 ecotypes was 0.69 and ranged from 0.32 to nea r 1.0. No relationship was observed between genetic similarity and geo graphical origin of the 28 ecotypes. The ecotype most distantly relate d to the other 27 was Niederzenz, with a mean genetic similarity of 0. 55 +/- 13. A bootstrap procedure was used to generate 200 random sampl es of bands of size n (n = 8, 12, 16,..., 55), and the coefficient of variance (CV) was estimated for each sample. The plot of the first two principal components provided a description of the relative genetic s imilarity among ecotypes. The results provide information useful to in vestigators interested in sampling the genetic variation among Arabido psis ecotypes.