Male gametic cell-specific expression of H2A and H3 histone genes

Formation of the generative cell in flowering plants initiates the male spe rmatogenesis pathway which eventually culminates in the process of double f ertilization. Little is known about the molecular mechanisms operative in t he generative cell. Here, we report the isolation and characterization of c DNA clones encoding generative cell-specific histones, gcH2A and gcH3. In s itu hybridization analysis revealed that both genes are activated after for mation of the generative cell and accumulation of transcripts increases pro gressively during generative cell maturation. These results suggest that gc H2A and gcH3 mRNAs are products of transcriptional activation of the genera tive cell nucleus and thus provide the first evidence for male germ line ce ll-specific gene expression in flowering plants.