Cytogenetic and molecular analysis of the multiple sex chromosome system of rumex acetosa

Abstract

A repeated sequence of 180 bp in tandem array has been isolated from the dioecious plant species Rumex acetosa which has a multiple sex chromosome system, XXQ/XY1Y2d. There are two or three thin C-bands on the X while the Ys are almost entirely heteropycnotic and DAPI-positive but contain no C-band material. The Ys thus represent massive blocks of facultative heterochromatin. The 180 bp sequence has been localized to the X and both Y chromosomes by in situ hybridization. The molecular data support an origin of the sex-multiple from a homomorphic chromosome pair rather than from a sex chromosome/autosome translocation. © 1994 The Genetical Society of Great Britain.