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

Abstract

Somatic chromosomes at mitotic metaphase of Bowenia serrulata, B. spectabilis and B. sp. ‘Tinaroo’ is investigated by the standard aceto-orcein staining method and the fluorescent in situ hybridisation method (FISH) with ribosomal DNA (rDNA) probe. Bowenia serrulata, B. spectabilis and B. sp. ‘Tinaroo’ each have a chromosome number of 2n = 18. The karyotype of B. serrulata exhibits 10 median-centromeric chromosomes, while B. spectabilis and B. sp. ‘Tinaroo’ exhibit eight median-centromeric chromosomes. By using FISH, B. serrulata, B. spectabilis and B. sp. ‘Tinaroo’ show a hybridisation signal on the satellite of the short arm of two submedian-centromeric chromosomes. However, the other hybridisation signal pattern is different among B. serrulata, B. spectabilis and B. sp. ‘Tinaroo’.