Submitted to: Acta Horticulturae
Publication Type: Book / chapter
Publication Acceptance Date: 7/31/2004
Publication Date: 2/1/2005
Citation: Danilova, T.V., Henning, J.A. 2005. Sex molecular markers reveal differences of y-chromosome molecular structure among hops of european and american origin. Acta Horticulturae. (ISHS) 668:85-92. Interpretive Summary: Hop is a dioecious crop producing both male and female plants from breeding crosses. As the female line is the only plant with economic importance, it would be desirable to have a molecular marker that could differentiate male offspring from female offspring while still in the seedling stage. We tested three different molecular markers on 66 different male lines from both European and American development. No single molecular marker differentiated all of the male plants. Nevertheless, molecular markers that were derived from plants of European descent did not identify males from American descent. It appears that there are differences in the genetic make-up of the Y-Chromosome between the two distinct 'races' of hop.
Technical Abstract: Hop, Humulus lupulus L, is a dioecious plant (2n=2x=20) with two heteromorphic sex chromosomes X and Y. The Y chromosomes of Native American and European male hops are morphologically different. Identification of sex is a common step in hop breeding. Molecular markers would allow detecting male hop plants at the seedling stage. We tested three presumed male-specific STS molecular markers on 66 male hop plants of American and European origin. About half of the male plants including males from Germany and Russia were detected by all three markers. The other male plants were not detected by the RAPD-based marker, while the two ISSR-based markers produced unexpected but reproducible major bands in these genotypes. Cluster analysis divided the male plants into two groups depending on the male ancestor. Male plants detected by all three STS markers are presumed to have Y chromosomes that originated from European hops.