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 cell division and subsequent progression through the cell cycle in Arabidopsis thaliana cell-suspension cultures were investigated. Partial synchronization of cells was achieved by a technique combining phosphate starvation and a transient treatment with the DNA replication inhibitor aphidicolin. Six cDNAs corresponding to genes highly induced in proliferating cells and showing cell-cycle-regulated expression were obtained by the mRNA differential display technique. Full-length cDNA clones (cH2BAt and cH2AvAt) corresponding to two of the display products were subsequently isolated. The cH2BAt clone codes for a novel histone H2B protein, whereas the cH2AvAt cDNA corresponds to a gene encoding a new member of the highly conserved histone H2A.F/Z subfamily of chromosomal proteins. Further studies indicated that H2AvAt mRNA expression is tightly correlated with cell proliferation in cell-suspension cultures, and that closely related analogs of the encoded protein exist in Arabidopsis. The implications of the conservation of histone H2A.F/Z variants in plants are discussed.