Estimation of ploidy levels and breeding backgrounds in pot carnation cultivars using flow cytometry and SSR markers.

摘要

We estimated the ploidy level of 45 pot carnation cultivars by means of flow cytometry (FCM). The results strongly suggested that 27 cultivars are diploid, 3 are triploid, and 15 are tetraploid. To verify the actual ploidy levels, we counted chromosome numbers in the root tips of one cultivar at each ploidy level. This revealed that 'Camille' was diploid, 'Baby Heart' was triploid, and 'Tula' was tetraploid. Our results suggested that the ploidy level varies among pot carnation cultivars. We analyzed the genotypes of 32 cultivars by using five simple sequence repeat (SSR) markers to estimate the correspondence with FCM ploidy levels and to analyze genetic diversity. Ploidy estimated from the maximum number of alleles per locus corresponded with that estimated by FCM among diploid and triploid cultivars, but not among tetraploids. Among diploid pot cultivars, we found only three or four alleles per locus, and most alleles were common to diploid cut cultivars. On the other hand, triploid and tetraploid pot cultivars had four to eight alleles per locus, and most were unique to given ploidy levels. SSR analysis suggested that diploid pot cultivars were derived from cut cultivars, while triploids and tetraploids were produced by crossing wild Dianthus spp. and similar genetic resources. In total, 30 pot cultivars with different ploidy levels could be successfully identified from the genotype of five SSR markers.