Effects of Anthropogenic Activities On Genetic Diversity of American Ginseng Growing in West Virginia

Genetic variation and structure of 12 wild and 10 cultivated populations of American ginseng growing under two levels of harvest pressure and cultivation intensity in West Virginia was assessed using random amplified polymorphic DNA (RAPD) markers.  Eight primers used generated a total of 98 discernable and reproducible bands of which 84 (85.71%) bands were polymorphic. Mean genetic diversity indices were high in wild populations from low harvest pressure region [percent polymorphism (P) = 33.33%, Nei's (1973) gene diversity (H) = 0.1172, and Shannon's index (I) = 0.1743] compared to populations from high harvest pressure region [P = 28.27%, H = 0.1019, I = 0.1513], however diversity measures were not significantly different (P > 0.05, Mann-Whitney test).  Analysis of molecular variance (AMOVA) further showed no significant genetic differentiation among regions (P = 0.7918), but genetic differentiation within populations (48.37%) and among populations (54.10%) were significant (P < 0.001). With regard to cultivation intensity, populations from a region with low cultivation intensity showed lower levels of genetic diversity (P = 29.93%, H = 0.0948, I = 0.1609) compared to populations from a region with high cultivation intensity (P = 60.60%, H = 0.2593, I = 0.3243), these diversity measures were significantly different (P < 0.05, Mann-Whitney test).  AMOVA further revealed that, in cultivated populations 53.68% and 42.11% of the total genetic variation was attributed to within and among population differentiation in regions respectively, and a small (4.20%) but significant variation was found among regions.  Differences in genetic diversity indices between wild populations from the two regions indicate that harvesting pressure may reduce genetic diversity of ginseng populations, although Mann-Whitney test and AMOVA did not indicate significant variation among these harvesting regions.  Significantly higher population genetic diversity evidenced in cultivated populations from a region with high cultivation intensity can be attributed to large scale growers sourcing seeds from a broad seed source to meet their cultivation scale. Whereas, lower diversity levels among populations in regions with less cultivation intensity will be due to small scale growers probably starting their crop from a narrow seed source, mostly from seeds collected from a single population in the wild or purchased from a single source. Key words: AMOVA, cultivation intensity, harvest pressure, Panax quinquefolius, RAPD.