Comparison between two genera, species and cultivars in Lactuceae, (3)

Estimation of DNA amounts (in arbitrary units) in two genera, two species, and three cultivars of one species, permits comparison between them and indicates that the biggest difference is between the two genera, Lactuca and Cichorium; but that the difference between the cultivars of Lactuca sativa is greater than the difference between Lactuca serriola and the mean for Lactuca sativa. Lactuca serriola is a presumed ancestor of Lactuca sativa. The most radiosensitive species, L. serriola, has slightly less DNA and smaller nuclear volume than the next most sensitive, L. sativa cult. Cos. This is discussed. (author)