Estimation of nuclear DNA content in Nasturtium R. Br. by flow cytometry

The most common and widespread species of Nasturtium in central Europe are the tetraploid Nasturtium officinale (2n = 4x = 32), the octoploid Nasturtium microphyllum (2n = 8x = 64), and their hexaploid hybrid Nasturtium × sterile (2n = 6x = 48). For the first time, flow cytometry was used to measure the genome size (2C DNA content) of these taxa. The highest nuclear DNA content was found in the octoploid N. microphyllum (2C = 1.43 pg) and the lowest in the tetraploid N. officinale (2C = 0.76 pg). Some differences in the amount of nuclear DNA were observed for the hexaploid N. × sterile (2C = 1.09–1.12 pg). Genome size analysis was thus proposed as a very useful tool for the identification of species of Nasturtium in their vegetative stage.