Trinucleotide microsatellite repeat is tightly linked to male sex in hop (Humulus lupulus L.)

Hop is a dioecious perennial, the female plants of which are cultivated for production of resin, used mainly in the brewing industry. Sex determination of hop plants is phenotypically determined in the second year of growth, so early sex determination at seedling stage, before planting, is important for breeding and cultivation purposes. We analyzed a microsatellite locus to determine sex specific differences in hop. Alleles of the locus showed tight linkage to male character, since no cross-over event was detected in two analyzed families with 181 progenies. The complete heterozygosity in 50 analyzed diverse males indicates a potential use of this marker for any desired parental pair. The marker is amplified in homologous chromosomes, which rules out incorrect determination of non-amplified samples, as can be the case with the dominant (presence/absence) type of markers. The described microsatellite locus is also highly variable, with 35 sized alleles, the distribution of which in different hop germplasms and their sequence variability are discussed. The sex specific marker determined in our study can contribute to studies of sex determination mechanisms and can be readily used in hop breeding and cultivation.