Comparison of karyotype and rDNA-distribution in somatic chromosomes of Bowenia species (Stangeriaceae, Cycadales)

Somatic chromosomes at mitotic metaphase of Bowenia serrulata, B. spectabil is and B. sp. 'Tinaroo is investigated by the standard aceto-orcein stainin g method and the fluorescent in situ hybridisation method (FISH) with ribos omal DNA (rDNA) probe. Bowenia serrulata, B. spectabilis and B. sp. 'Tinaro o each have a chromosome number of 2n = 18. The karyotype of B. serrulata e xhibits 10 median-centromeric chromosomes, while B. spectabilis and B. sp. 'Tinaroo exhibit eight median-centromeric chromosomes. By using FISH, B. se rrulata, B. spectabilis and B. sp. 'Tinaroo show a hybridisation signal on the satellite of the short arm of two submedian-centromeric chromosomes. Ho wever, the other hybridisation signal pattern is different among B. serrula ta, B. spectabilis and B. sp. 'Tinaroo.