The Y chromosome-specific STS marker MS2 and its peripheral regions on the Y chromosome of the dioecious plant Silene latifolia.
Sex determination in Silene latifolia uses the XX/XY system. The recent evolution of dioecy in S. latifolia provides a unique opportunity to study the early stages of Y chromosome evolution. However, the current Y chromosome map still contains many large gaps with no available markers. In this study, a sequence tagged site (STS) marker, MS2, was isolated and mapped to the same locus as L8 on the Y chromosome. To investigate the peripheral regions of MS2, a bacterial artificial chromosome (BAC) library was constructed from a male plant, and the BAC clone containing MS2 (MS2-9d12F) was isolated from 32 640 clones with an average insert size of 115 kb. A 109-kb insert of the BAC clone was analyzed. BLASTX analysis showed 11 sequences similar to some known proteins, most of which are retrotransposon-like elements. The ORF Finder predicted 9 ORFs within MS2-9d12F. RT-PCR analyses revealed that only 4 of the 9 predicted ORFs are expressed in both male and female plants. These 4 ORFs are candidates for genes having counterparts on both the X and Y chromosomes. Dot-matrix plot analysis and a BLASTN search revealed LTR-like sequences close to the retrotransposon-like elements and high similarity to 3 known genomic sequences of S. latifolia. These results suggest an accumulation of retrotransposons and segmental duplications in peripheral regions of MS2 during the early stage of sex chromosome evolution.
Ishii
Kotaro
K
Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8562, Japan.
Sugiyama
Ryuji
R
Onuki
Megumi
M
Kazama
Yusuke
Y
Matsunaga
Sachihiro
S
Kawano
Shigeyuki
S
D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial; D032461:Chromosomes, Plant; D018744:DNA, Plant / Q000737:chemistry; D019143:Evolution, Molecular; D017343:Genes, Plant; D005819:Genetic Markers; D023281:Genomics; D017404:In Situ Hybridization, Fluorescence; D018626:Retroelements; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D016324:Sequence Tagged Sites; D019849:Sex Determination Processes; D029751:Silene / Q000235:genetics*; D020079:Terminal Repeat Sequences
D018744:DNA, Plant; D005819:Genetic Markers; D018626:Retroelements