Abstract
A dioecious plant, Silene latifolia, has heteromorphic XY-type sex chromosomes. Because the sex chromosomes of this species are largest of the karyotype, its structural analysis using fluorescent in situ hybridization (FISH) is easy to be performed. Sex chromosomes are thought to be derived from a pair of autosomes that have been progressively differentiated by the suppression of recombination around locus controlling sex determination, and thereafter unrecombining regions have developed with sex determination genes. On the other hand, a recombining region called pseudoautosomal regions (PAR) is needed to uniformly divide the sex chromosomes in meiosis. We determined the positions of the pseudoautosomal regions (PAR) of the sex chromosomes by the detailed characterization of repetitive sequences on chromosomal ends. Another interesting phenomenon in S. latifolia is that infection of a smut fungus (Microbotryum violaceum) induces the stamen elongation in the female flower, resulting in producing the hermaphroditic flowers. Analysis of the infected females as counter parts of the males may improve our knowledge of the stamen promoting function (SPF) of the Y chromosome. Thus we performed the expression analyses of genes related to stamen elongation in the smut-infected female plant.
