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 Arabidopsis thaliana. Twenty-five previously mapped genomic clones were used as probes in Southern hybridizations to detect restriction fragment length polymorphisms (RFLPs). A total of 62 polymorphic restriction fragments were classified as to their presence or absence for each genotype. The genetic similarity between each pair of ecotypes was calculated 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 near 1.0. No relationship was observed between genetic similarity and geographical origin of the 28 ecotypes. The ecotype most distantly related to the other 27 was Niederzenz, with a mean genetic similarity of 0.55 ± 13. A bootstrap procedure was used to generate 200 random samples 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 similarity among ecotypes. The results provide information useful to investigators interested in sampling the genetic variation among Arabidopsis ecotypes.