Dapi-Fluorescence Intensity Discriminates Between The Taxa In The Genus Reynoutria
J Suda1,2, B Mandák2 and K Bímová2,3
1 Department of Botany, Charles University, Benátská 2, Prague, CZ-128 01, Czech Republic
2Institute of Botany, Academy of Sciences of the Czech Republic, Pruhonice 1, CZ-252 43, Czech Republic
3Institute of Applied Ecology, Czech Agricultural University Prague, CZ-281 63, Kostelec nad Cernými lesy, Czech Republic
Representatives of the genus Reynoutria (knotweed) rank among the most dangerous alien plants introduced to Europe. Three taxa spread rapidly in various man-made and semi-natural habitats: R. japonica (with two varieties - tetraploid var. compacta and octoploid var. japonica), R. sachalinensis (mostly tetraploid), and a taxon of hybridogenous origin R. ×bohemica (predominantly hexaploid). A variation in ploidy levels (4x, 6x, 8x) in the latter two taxa has been revealed recently in the Czech Republic1. Subsequent investigations using DAPI-flow cytometry detected an inter-species differentiation in the nuclei fluorescence intensity between plants with the same number of chromosomes. The relative fluorescence of the monoploid chromosome sets in R. japonica, R. ×bohemica, and R. sachalinensis were 100, 93.9-95.7 and 88.7-91.3 respectively.
The values suggested that:
1. R. japonica var. japonica is an autopolyploid descendant of var. compacta;
2. hexaploid R. sachalinensis arose by a fusion of non-reduced and reduced gametes of the tetraploid individual, the origin of the octoploid cytotype remaining rather speculative;
3. all the ploidy levels in R. ×bohemica arose by a hybridization between the corresponding cytotypes of R. sachalinensis and R. japonica.
1. Mandák B, Pysek P, Lysák MA, Suda J, Krahulcová A, Bímová K (2003). Annals of Botany 92: 265-272.