1995 Fiscal Year Final Research Report Summary
Analysis of defense mechanism against Agrobacterium-reinfection in plants regenerated from hairy roots.
Project/Area Number |
06806010
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Research Category |
Grant-in-Aid for General Scientific Research (C)
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Allocation Type | Single-year Grants |
Research Field |
応用微生物学・応用生物化学
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Research Institution | Tokai University |
Principal Investigator |
MANO Yoshihiro Tokai University, School of High Technology for Human Welfare, Associate Professor, 開発工学部, 助教授 (20219538)
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Project Period (FY) |
1994 – 1995
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Keywords | Hairy root / Agrobacterium / Ri plasmid / T-DNA / Transgenic Plant / Immune-like response / Gene expression / Plant molecular biology |
Research Abstract |
Agrobacterium rhizogenes 15834 and Agrobacterium tumefaciens LBA4404 harboring pBI121 infected tobacco BY-2 cells, forming hairy root cells and kanamycin-resistant (Km^R) cells, respectively. However, no Km^R-transformant of hairy root cells was obtained by introducing the neomycin phosphotransferase II (NPT II) gene on the T-DNA of pBI121 into the hairy root cells, although the hairy root cells of Km^R clones were obtained by introducing Ri T-DNA into Km^R clones. The similar results were obtained using the wild-type tobacco plant, the plants regenerated from hairy root clones and Km^R transgenic plants of Nicotiana plumbaginifolia. These transformation experiments suggest that transgenic plants which have been already transformed by Ri T-DNA cannot undergo a second Agrobacterium-mediated T-DNA transformation. Plants carrying Ri T-DNA,which is integrated into the host chromosome analogously with lambda phage DNA,are possibly immune to further infection with Agrobacteria. Both characteristics of the kanamycin resistance and the phytohormone-independent growth were stably maintained in the hairy root clones derived from the Km^R transgenic plants after culturing in the medium without kanamycin for 8 months. These results show that two types of T-DNA coexist and the genes on the T-DNAs are normally expressed in the plant genome. When NPT II gene was directly introduced into the tobacco protoplasts by electroporation, Km^R cells were obtained from BY-2 cells but not from the hairy root cells. The process of infection with Agrobacteria can be separated into the four stages ; (1) Attachment to the plant cells, (2) T-DNA transfer to the plant cells, (3)T-DNA integration into the plant genome, and (4) Gene expression from the integrated T-DNA.These results show that the "immune" response in the plant cells carrying Ri T-DNA may be occurred in the stage of T-DNA integration into the plant genome.
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Research Products
(6 results)