植物の生長に関る情報伝達系の研究

概要

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Exposure of normal, tall rice(Oryza sativa)seedlings to 5-azacytidine, a powerful inhibitor of DNA methylation in vivo, induced both demethylation of genomic DNA and dwarf plants. Genes that had been affected by teatment were identified by differential screening of a cDNA library, and a gene encoding a small GTP binding protein, rgp1, was subsequently isolated. To determine the physiological role of rgp1, the coding region of rgp1 was introduced into tobacco plants. Transformants showed distinct phenotypic changes; reduced apical dominance and dwarfism. The content of cytokinins was 6-fold higher in transgenic plants that in control wild-type plants. Looking for genes that respond to cytokinins, a protein kinase gene, wpk4 was isolated. In addition to cytokinin treatment, transcripts of wpk4 were increased upon poor nutrients and light. Cytokinin antagonist erased these effects, suggesting that nutrient and light signals were mediated by cytokinins. Our experiments have revealed that DNA methylation controls expression of genes involved in plant growth, and that protein phosphorylation cascade that is regulated by cytokinins is at least a part of signal transduction pathways of plant growth. Further experiments are under progress to determine components that participate in these pathways.
植物化学調節学会の論文
1998-10-01