ENDOPOLYPLOIDY PATTERNS IN ORGANS OF TRIFOLIUM SPECIES (FABACEAE)

Abstract

The pattern of endopolyploidy in the genus Trifolium was studied in mature organs of T. montanum and T. repens at reproductive stage, with comparative data for T. pratense, all from natural populations. Endopolyploidy in root, stem, petiole, leaf, inflorescence stalk, sepal, petal, stamen and carpel was detected by flow cytometry. 2C, 4C and 8C nuclei were found in organs of T. montanum and T. repens, and additionally 16C nuclei in organs of T. repens. The organs of T. montanum and T. repens differed in degree of endopolyploidy based on cycle values calculated from flow cytometry data; it was lowest in leaf and sepal in T. montanum and T. repens, and highest in T. montanum in petal and carpel and in T. repens in petiole and inflorescence stalk. These results are also seen in the two or more peaks of interphase nuclei in the flow cytometry histograms. There were significant correlations between the organs of T. pratense and T. repens as well as substantial differences between Trifolium species in the degree of endopolyploidy. T. pratense showed higher absolute endopolyploidy than T. montanum and T. repens. Principal component analysis showed that individuals of T. repens and T. montanum are more similar to each other than to individuals of T. pratense in degree of endopolyploidy. The observed variation between species might be explained by phylogenetic relationships and genome size differences.