Analysis and evolution of two functional Y-linked loci in a plant sex chromosome system.
White campion (Silene latifolia) is one of the few examples of plants with separate sexes and with X and Y sex chromosomes. The presence or absence of the Y chromosome determines which type of reproductive organs--male or female--will develop. Recently, we characterized the first active gene located on a plant Y chromosome, SlY1, and its X-linked homolog, SlX1. These genes encode WD-repeat proteins likely to be involved in cell proliferation. Here, we report the characterization of a novel Y-linked gene, SlY4, which also has a homolog on the X chromosome, SlX4. Both SlY4 and SlX4 potentially encode fructose-2,6-bisphosphatases. A comparative molecular analysis of the two sex-linked loci (SlY1/SlX1 and SlY4/SlX4) suggests selective constraint on both X- and Y-linked genes and thus that both X- and Y-linked copies are functional. Divergence between SlY4 and SlX4 is much greater than that between the SlY1 and SlX1 genes. These results suggest that, as for human XY-linked genes, the sex-linked plant loci ceased recombining at different times and reveal distinct events in the evolutionary history of the sex chromosomes.
Atanassov
I
I
Laboratoire de Reproduction et Développement des Plantes, Ecole Normale Supérieure Lyon, Lyon, France.
Delichère
C
C
Filatov
D A
DA
Charlesworth
D
D
Negrutiu
I
I
Monéger
F
F
D002875:Chromosomes / Q000235:genetics*; D019143:Evolution, Molecular; D015723:Gene Library; D017343:Genes, Plant; D006801:Humans; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018514:Plant Structures / Q000737:chemistry; D029751:Silene / Q000235:genetics*
D010940:Plant Proteins