Determination of Chromosome Numbers and Genome Sizes in Six Species of Byblis (Byblidaceae)

Chromosome numbers and 2C-values of six Byblis species were determined to investigate the chromosome differentiation and genome diversity in this genus. Somatic chromosome numbers of the B. liniflora complex showed the diploid and the tetraploid numbers of 2n=16 and 32. In contrast, the chromosome number of B. gigantea, which belongs to the B. gigantea complex, displayed only the tetraploid numbers of 2n=36. The 2C DNA contents across all species studied were over a three-fold range, from the lowest value of 2C=0.64 pg in B. rorida to the highest value of 1.93 pg in B. gigantea. Since two cytotypes with different ploidy levels were seen in B. filifolia, the 2C contents of 0.70 pg and 1.81 pg were measured in the diploid (2n=2x=16) and the tetraploid (2n=4x=32), respectively. Haploid genome sizes of the tetraploid B. filifolia were, thus, 1.3 times larger than that of the diploid. The lowest haploid value of 1Cx=271 Mbp was shown in B. guehoi.