Submitted to: Acta Horticulturae
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/24/2004
Publication Date: 2/1/2005
Citation: Hummer, K.E., Oliphant, J.M., Taylor, A., Deinzer, M., Jackson, J. 2005. Xanthogalenol and 4'-o-methylxanthohumol content of american hop species. Acta Horticulturae. 668:229-232. Interpretive Summary: Some species of hop plants produce specific chemicals. We collected wild hops from 9 mid-western and western American states and analyzed for the presence of a specific flavonoids. In two species of hop plants from the Eastern and Mid-Western United states and Canada, a particular 4'-chemical was found. This chemical was not present in hop plants in the Western United States or in hop plants wild in Europe. In one hop species that is found on both sides of the Rocky Mountains, the 4'-chemical was present in some specimens but not in others. In a few places, such as the Kaibab Plateau, Arizona, and Phantom Canyon, Colorado, plants with and without the 4'-chemical were found growing near one another. Further morphological and molecular evaluations of this wild collected germplasm are in process. The significance of the presence of this 4'chemical is being researched.
Technical Abstract: The resins produced by either lupulin or leaf glands of more than 41 genotypes of botanical varieties of Humulus lupulus L. collected from the wild in 9 mid-western and western American states were analyzed for the presence of prenylated flavonoids. A dichotomous distribution, i.e., the presence or absence, of 4'-O-methylchalcones in wild, American-collected hops was confirmed. Xanthogalenol and other 4'-O-methylchalcones were ubiquitous in H. lupulus var. lupuloides E. Small and in H. l. var. pubescens E. Small. Both of these botanical varieties are distributed in mid-western North America, east of the Rocky Mountain divide, in the Missouri-Mississippi River basin. Presence of the 4'-O-methylchalcones was inconsistent between specimens of H. lupulus var. neomexicanus Nelson and Cockerell. This species is primarily distributed in western states but also extends across the divide to the Missouri-Mississippi River drainage. Most of the H. l. var. neomexicanus collected east of the divide contained 4'-O-methylchalcones as did H. l. var. lupuloides and H. l. var. pubescens, while most specimens of H. l. var. neomexicanus from west of the divide did not. In a few localities, such as the Kaibab Plateau, Arizona, and Phantom Canyon, Colorado, genotypes of H. l. var. neomexicanus containing 4'-O-methylchalcones and those without, were sympatric. Further morphological and molecular evaluations of this wild collected germplasm are in process.