title: Sex chromosome differentiation in Humulus japonicus Siebold & Zuccarini, 1846 (Cannabaceae) revealed by fluorescence in situ hybridization of subtelomeric repeat.
abstract: Humulus japonicus Siebold et Zucc (Japanese hop) is a dioecious species of the family Cannabaceae. The chromosome number is 2n = 16 = 14 + XX for females and 2n = 17 = 14 + XY1Y2 for male. To date, no fluorescence in situ hybridization (FISH) markers have been established for the identification of Humulus japonicus sex chromosomes. In this paper, we report a method for the mitotic and meiotic sex chromosome differentiation in Humulus japonicus by FISH for HJSR, a high copy subtelomeric repeat. The signal is present in the subtelomeric region of one arm of the X chromosome. We demonstrate that males have two Y chromosomes that differ in FISH signal with the HJSR probe. Indeed, the HJSR probe hybridizes to a subtelomeric region on both arms of chromosome Y1 but not of chromosome Y2. The orientation and position of pseudoautosomal regions (PAR1 and PAR2) were also determined.
authors.affiliation: Centre for Molecular Biotechnology, Russian State Agrarian University - Moscow Timiryazev Agricultural Academy, Moscow 127550, Timiryazevskaya Street, 49, Russia.
authors.forename: Oleg S
authors.initials: OS
authors.lastname: Alexandrov
authors.forename: Mikhail G
authors.initials: MG
authors.lastname: Divashuk
authors.forename: Nikolay A
authors.initials: NA
authors.lastname: Yakovin
authors.forename: Gennady I
authors.initials: GI
authors.lastname: Karlov
keywords: Humulus japonicus; fluorescence in situ hybridization; sex chromosomes; sex determination in plants; subtelomeric repeat