| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
A soil bacterium Agrobacterium tumefaciens induces crown gall disease on many plants. Tumorous tissues display various phenotypes on the culture medium. We assumed that in these tissues, the genes involved in plant differentiation could be induced or repressed, and thus current project is directed to isolation and characterization of such genes. We first generated shoot-forming and unorganized calli in tobacco plants upon introduction of auxin and cytokinin biosynthesis genes, and 6b gene which modulates the effects of these plant growth substances. Complementary DNA was synthesized from these tissues and screened for differential expression by differential hybridization and differential display techniques. Five clones and four clones were found to be preferentially expressed in shoot-forming callus and unorganized callus respectively. The former clones were homologous to the genes encoding 14kD protein from carrot, SAR8.2 associated with tobacco mosaic virus infection, heat shock protein, chlorophyll a apoprotein psaB,and ribonucleoprotein from tobacco. The latter clones were similar to tobacco chitinase, ribosomal protein L29 from Arabidopsis, allergenic protein Lolpl from rye, and as yet unknown clone termed 1-22A.Particularly, the 14kD-protein gene has been reported to be associated with regeneration of carrot cells, and hence we cloned our homologue under the control of CaMV35S promoter in an antisense orientation, and introduced to tabacco. Unfortunately, resulting transgenic plants did not show any phenotypic abnormality. However, the gene expression was induced by wounding, which suggest that the 14kD-protein gene is involved in stress response. Finally, the psaB and ribonucleoprotein gene seem to be required for chloroplast development, and further investigation is necessary to determine the relationship between plastid and total plant development.
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