Abstract Background Expressed sequence tag EST databases represent a valuable resource for the identification of genes in organisms with uncharacterized genomes and for development of molecular markers.
Here I demonstrate that four genes that are X-linked in S. I also report a genetic map for four S. The order of the genes on the S. IT has been suggested that sex chromosomes evolve from a pair of homologous autosomes proto sex chromosomeswhich stop recombining with each other and gradually diverge into mostly nonhomologous X and Y chromosomes Ohno ; Bull Alternatively, sex chromosomes could have evolved in several stages, through consecutive translocations of autosomal fragments to the proto- sex chromosomes and gradual expansion of the nonrecombining region.
Y-linked genes advantageous in males and detrimental in females may possess a selective advantage, promoting translocation of autosomal regions containing sexually antagonistic genes to the Y chromosome, as well as further expansion of the nonrecombining region on the Y chromosome Charlesworth and Charlesworth ; Bull ; Rice Indeed, the distal regions of the human sex chromosomes are autosomal in marsupials Spencer et al.
Mouse Sandstedt and Tucker and bird Handley et al. It is not clear, however, whether the stepwise formation of the sex chromosomes is a general process or is confined to mammals and birds.
Studying the origins of sex chromosomes in model organisms, such as Drosophila, mouse, human, and chicken is extremely difficult, as they arose hundreds of millions of years ago. Many organisms, however, have much younger sex chromosomes [e. In particular, the plant genus Silene is very convenient for studying the early stages of sex chromosome evolution because sex chromosomes in this genus have been found only in a small cluster of dioecious Silene species section Elisanthe: The rest of the Silene genus is nondioecious exept S.
Silent divergence between dioecious S. Degeneration has probably started on the S.
The silent divergence between the homologous S. It is not known, however, whether the order of the genes on the X supports the evolutionary strata model. Such translocations are probably quite common because they were reported for many insect Bachtrog and Charlesworth ; Jacobsmammalian Watson et al.
Thus, without knowing the order of the genes on the Silene X chromosome, and without comparisons with the closely related nondioecious Silene species, it is difficult to infer the sequence of events that has led to the formation of the Silene sex chromosomes.
To shed light on the evolutionary history of the S. The MROS3X Guttman and Charlesworth has not been used because this gene is a member of a multicopy gene family with multiple autosomal copies Kejnovsky et al.
Thus, the segregation of the alleles in these genes was inferred from the electrophoretic mobility of PCR products on 1.
Direct sequencing of the SlssX PCR product from the maternal and paternal individuals of the family 5 Filatov revealed two nucleotide positions heterozygous in the female and hemizygous in the male. As none of these polymorphisms were located at restriction sites, the segregation of the SlssX gene was tested by direct sequencing of the PCR products of all the F1 progeny.The sex chromosomes of dioecious white campion, Silene latifolia (Caryophyllaceae), are of relatively recent origin (10–20 million years), providing a unique opportunity to trace the origin and evolution of sex chromosomes in this genus by comparing closely related Silene species with and without sex chromosomes.
The dioecious white campion Silene latifolia (syn. Melandrium album) has heteromorphic sex chromosomes, XX in females and XY in males, that are larger than the autosomes and enable their separation by flow sorting. The group of MROS genes, the first male-specifically expressed genes in dioecious plants, was recently identified in S.
Older taxonomic treatments place S. latifolia subsp. alba in the genus Lychnis, which differs from Silene in very small structural details of the flowers; however, Robinson and Fernald () record both L.
alba and S.
latifolia, while other botanists record this species as S. alba.
Silene latifolia (formerly Melandrium album), the white campion is a dioecious flowering plant in the family Caryophyllaceae, native to most of Europe, Western Asia and Northern Africa. It is a herbaceous annual, occasionally biennial or a short-lived perennial plant, growing to between 40–80 centimetres tall.
The White Campion’s Masculinity Crisis. The Y chromosome of the White Campion (Silene latifolia) has undergone genetic degradation, losing some genes entirely from its Y chromosome.
Charlotte Gardener, Danielle Hewson, Abbie O’Connor, Francis Windram. This year, Bergero et al. RESEARCH ARTICLE Open Access Identification of white campion (Silene latifolia) guaiacol O-methyltransferase involved in the biosynthesis of veratrole, a key volatile for.