Abstract

Flow cytometry analysis of propidium iodide (PI) stained nuclei isolated from leaf tissues was used to estimate the genome size of American ginseng (Panax quinquefolius L.) and evaluate inhibitory effects of its secondary compounds on PI intercalation. American ginseng nuclear DNA content was estimated to be 10.05 ± 0.04 pg/2C, and therefore its haploid (1C) genome size is 4914 Mbp. There was no significant inhibition of PI fluorescence of reference standard nuclei co-processed with American ginseng. This indicates that secondary compounds of American ginseng do not interfere with PI intercalation. By comparison, the genome size of American ginseng is 31.30 and 10.03 times bigger than that of Arabidopsis thaliana and Oryza sativa, respectively, and is 1.58 times bigger than that of its sister species Panax ginseng C.A. Meyer (Asian ginseng). Thelarge genome size of American ginseng will have valuable implications on its sequencing,structural and functional genomics research.

Key words: Panax quinquefolius, flow cytometry, ginsenosides, propidium iodide.