Flow cytometry estimation of nuclear size and ploidy level of habituated calli of sugar beet

A fully habituated (auxin- and cytokinin-independent) self-regenerating (or ganogenic) sugar beet cell line (HO) and a fully habituated non-organogenic one (HNO) derived from the former one, were analyzed as to their nuclear s ize and DNA content. Flow cytometry and image analysis were used and cells of certified diploid leaves of the same sugar beet strain served as control s. The HNO cells had been shown previously to have many characteristics of cancerous cells. The analyses made on leaves and HNO cells indicated the pr esence of only one population of cycling cells. In HO cells. two cycling po pulations were detected: the first one had the same DNA content as the leav es while the second one contained two fold more DNA than the first populati on. HNO cells showed the higher nuclear size and DNA content. HNO cells als o showed evidence of aneuploidy. Thus, nuclear size, DNA content and ploidy level increase together with the neoplasic progression to culminate in HNO cells with the loss of organogenic totipotency.