Abstract
Ocimum spp. are cultivated worldwide for culinary and medicinal uses. Some species are the subjects of improvement in breeding programs while others are still collected from the wild. Polyploidy and dysploidy are common features of the cultivated species. Taxonomical confusion has arisen in the classification of Ocimum spp., in part due to the ease with which many of the species intercross and the morphological similarities between several of the species. Flow cytometry is a fast and easy method to measure nuclear DNA content and could be a useful tool to assess germplasm accessions in a breeding program. Here we report the first estimates of nuclear DNA content of eight Ocimum spp., as determined by flow cytometry. The 2C nuclear DNA content ranged from 928 (O. campechianum) to 5515 Mbp (O. americanum). The nuclear DNA content levels may be useful for better understanding of the taxonomical relationships among species.