Isolation of Y chromosome-specific sequences from Silene latifolia and mapping of male sex-determining genes using representational difference analysis

The genomic subtraction method representational difference analysis (RDA) was used to identify male-specific restriction fragments in the dioecious plant Silene latifolia. Male-specific restriction fragments are linked to the male sex chromosome (the Y chromosome). Four RDA-derived male-specific restriction fragments were used to identify polymorphisms in a collection of X-ray generated mutant plants with either hermaphroditic or asexual flowers. Some of the mutants have cytologically detectable deletions in the Y chromosome that were correlated with loss of male-specific restriction fragments. One RDA-derived probe detected a restriction fragment present in all mutants, indicating that each has retained Y chromosomal DNA. The other three probes detected genomic fragments that were linked in a region deleted in some hermaphroditic and some asexual mutants. Based on the mutant phenotypes and the correlation of cytologically visible deletions with loss of male-specific restriction fragments, these markers were assigned to positions on the Y chromosome close to the carpel suppression locus. This RDA mapping also revealed a Y-linked locus, not previously described, which is responsible for early stamen development.