An STS Marker, Y202, Located on the Silene latifolia Y Chromosome between the Chromosomal Distal-end Satellite DNA and SlY1

Abstract

The pseudoautosomal region (PAR) is the chromosomal region where XY sex-chromosome pairing occurs. The boundary of the PAR delineates the XY pairing and non-pairing regions, but detailed information about this region is lacking. In this study, we analyzed the sequences adjacent to SlX1 and SlY1 in the dioecious plant Silene latifolia. SlX1 and SlY1, which are linked to the X and Y sex chromosomes, respectively, are thought to be closely linked to the PAR. The Sl-distal-satDNA is a satellite DNA found at the ends of S. latifolia chromosomes. The chromosomal distance between SlX1/SlY1 and Sl-distal-satDNA has not been examined. It was probably almost entire the PAR. However, the region between SlY1 and the Sl-distal-satDNA could be amplified in PCR. The nucleotide sequence between SlY1 and the Sl-distal-satDNA was determined following PCR amplification and compared to the sequence adjacent to SlX1 using BAC clones. In addition, a new male-specific STS marker, Y202, was designed based on the sequence adjacent to SlY1. Y202 as well as SlY1 were mapped on the Y chromosome using a panel of deletion mutants and FISH analysis. Our data suggest that the sequences adjacent to SlX1 and SlY1 do not simply follow a gradient of sequence divergence, a feature that was thought to allow the functioning of the PAR boundary. Therefore, recombination suppression in the XY chromosomes probably occurs via other mechanisms.