| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2004: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
The aim of this study was to establish super-high efficient foreign protein expression system in plants by controlled expression of a plant virus based vector and silencing suppressors, which prevents specific degradation of viral vector RNA in a later stage of the infection. Genes of three silencing suppressors, cucumber mosaic virus 2b, tomato bushy stunt virus p19 and tomato spotted wilt virus. NSs, which suppressed gene silencing by possibly different mechanisms, were introduced to estradiol-and dexamethasone-inducible expression vectors, and transformed into Nicotiana benthamiana plants. Transgenic plants that inducibly expressed one of these suppressors were successfully produced. However, the expression of the suppressors in the cross-progenies that had two or three different suppressors were often significantly suppressed, suggesting a synergistic adverse effect of these suppressors. Next, transgenic plants that inducibly expressed one of the silencing suppressors and a replicable brome mosaic virus (BMV)-based vector by treatment of dexamethasone were successfully produced by crossing of the transgenic plants. Significantly, in the transgenic plants that inducibly expressed NSs and the BMV vector, the decreasing of the viral RNA and the foreign protein encoded in the vector, which was usually observed in a later stage of the infection, was suppressed. Various useful proteins may be produced in transgenic plants that inducibly express NSs and a BMV vector.
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