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Hop ( Humulus lupulus L.) is dioecious species with female plants of commercial value. During breeding process it is desirable to identify the sex of hop plants at the stage of seedling. Twenty two inter simple sequence repeat (ISSR) primers were screened on female and male hop genotypes of Russian and European origin. Two ISSR primers revealed fragments specific for male plants of hop. Based on the sequences two pairs of primers were designed. These male specific sequence tagged site (STS) markers were tested on male hop accessions of Russian origin and female hop accessions of Russian, European and American origin. A high homology of male specific hop DNA sequences to expressed sequences from EMBL plants EST database was found, most of which code cell wall glycoproteins. The applicability of ISSR-PCR analysis for development of sex molecular markers in hop is discussed. [ABSTRACT FROM AUTHOR]

Hop (Humulus lupulus L.) was karyotyped by Fluorescence In Situ Hybridization (FISH) with probes 18S-25S and 5S rDNA as well as DAPI banding and measurements of lengths of chromosome. Irrespective of the sex of the plants these probes revealed one signal near the telomere of chromosome 6 and two signals each on chromosomes 2 and 5. The shortest chromosome in a metaphase plate of a male plant was designated to be chromosome Y. It displayed neither signals with FISH nor DAPI bands. A middle sized metacentric chromosome with no telomeric but with an interstitial DAPI band on the short arm was designated as X. All autosomes displayed telomeric DAPI-positive bands. For the first time all mitotic hop chromosomes including the sex chromosomes were identified by methods of molecular cytogenetics. [ABSTRACT FROM AUTHOR]