Chromosome landmarks and autosome-sex chromosome translocations in Rumex hastatulus, a plant with XX/XY1Y2 sex chromosome system.
Rumex hastatulus is the North American endemic dioecious plant with heteromorphic sex chromosomes. It is differentiated into two chromosomal races: Texas (T) race characterised by a simple XX/XY sex chromosome system and North Carolina (NC) race with a polymorphic XX/XY1Y2 sex chromosome system. The gross karyotype morphology in NC race resembles the derived type, but chromosomal changes that occurred during its evolution are poorly understood. Our C-banding/DAPI and fluorescence in situ hybridization (FISH) experiments demonstrated that Y chromosomes of both races are enriched in DAPI-positive sequences and that the emergence of polymorphic sex chromosome system was accompanied by the break of ancestral Y chromosome and switch in the localization of 5S rDNA, from autosomes to sex chromosomes (X and Y2). Two contrasting domains were detected within North Carolina Y chromosomes: the older, highly heterochromatinised, inherited from the original Y chromosome and the younger, euchromatic, representing translocated autosomal material. The flow-cytometric DNA estimation showed ∼3.5 % genome downsizing in the North Carolina race. Our results are in contradiction to earlier reports on the lack of heterochromatin within Y chromosomes of this species and enable unambiguous identification of autosomes involved in the autosome-heterosome translocation, providing useful chromosome landmarks for further studies on the karyotype and sex chromosome differentiation in this species.
Department of Plant Breeding and Seed Science, University of Agriculture in Cracow, Łobzowska 24, 31-140, Cracow, Poland, rrjoachi@cyf-kr.edu.pl.
Aleksandra
A
Grabowska-Joachimiak
Adam
A
Kula
Tomasz
T
Książczyk
Joanna
J
Chojnicka
Elwira
E
Sliwinska
Andrzej J
AJ
Joachimiak
D002871:Chromosome Banding; D032461:Chromosomes, Plant; D005819:Genetic Markers; D017404:In Situ Hybridization, Fluorescence; D059785:Karyotype; D031804:Rumex / Q000235:genetics*; D012730:Sex Chromosomes; D014178:Translocation, Genetic
D005819:Genetic Markers