DNA content variation in the genus Arabidopsis. Variation in nuclear DNA contents (reference standard set as 1) among major gene pools of Arabidopsis (excluding A. thaliana and hybridogenous taxa) determined by flow cytometry of 143 accessions from throughout Europe and Japan. Fluorescence intensity of Solanum pseudocapsicum was set to a unit value. Letters indicate significantly different groups at α = 0.05 as indicated by TukeyHSD post-hoc multiple comparison test (diploid and tetraploid accessions were tested separately; *were marginally significant at p = 0.055). The values represented by lines, boxes and whiskers are median, quartiles and range (min-max), respectively.