IDENTIFICATION OF PROLIFERATION-INDUCED GENES IN ARABIDOPSIS-THALIANA- CHARACTERIZATION OF A NEW MEMBER OF THE HIGHLY EVOLUTIONARILY CONSERVED HISTONE H2A.F Z VARIANT SUBFAMILY/

The changes in gene expression associated with the reinitiation of cel l division and subsequent progression through the cell cycle in Arabid opsis thaliana cell-suspension cultures were investigated. Partial syn chronization of cells was achieved by a technique combining phosphate starvation and a transient treatment with the DNA replication inhibito r aphidicolin. Six cDNAs corresponding to genes highly induced in prol iferating cells and showing cell-cycle-regulated expression were obtai ned by the mRNA differential display technique. Full-length cDNA clone s (cH2BAt and cH2AvAt) corresponding to two of the display products we re subsequently isolated. The cH2BAt clone codes for a novel histone H 2B protein, whereas the cH2AvAt cDNA corresponds to a gene encoding a new member of the highly conserved histone H2A.F/Z subfamily of chromo somal proteins. Further studies indicated that H2AvAt mRNA expression is tightly correlated with cell proliferation in cell-suspension cultu res, and that closely related analogs of the encoded protein exist in Arabidopsis. The implications of the conservation of histone H2A.F/Z v ariants in plants are discussed.