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[SANET-MG] sustainable agriculture creates ricin cry!aC toxin fusion gene for rice and maize
Ricin is one of the most toxic natural toxins known. At first glance it
does not seem entirely sustainable like to modify maize and rice with
the gene for a toxin that would likely kill everyone on earth. Of
course that might be an idea to save the environment. Seriously, ricin
has two protein chains, A that kills by damaging ribosomes and B a
lectin that binds to animal cell membrane galactose residues and
enhances A entering the cell. Only the B chain lectin gene is used to
enhance the action of Bt cry1Ac toxin. The constructed gene contained
also included an antibiotic marker gene ,promoter, antibiotic resistance
gene and transcription terminator.
The ricin B cry1AB fusion protein should require extensive safety
testing and it cannot be said to substantially equivalent to unmodified
rice and maize. I object , in principle, to linking such high risk
genetic constructs to "sustainable agriculture".
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0502871102
An alternative strategy for sustainable pest resistance in genetically
enhanced crops
( Bt genes | transgenic plants | transgenic maize | transgenic rice )
Luke Mehlo *, Daphrose Gahakwa , Pham Trung Nghia , Nguyen Thi Loc ,
Teresa Capell ¶, John A. Gatehouse , Angharad M. R. Gatehouse ||**, and
Paul Christou ¶**
*Scientific and Industrial Research and Development Centre, 1574 Alpes
Road, Hatcliff, Harare, Zimbabwe; Uganda National Seed Certification
Services, P.O. Box 7065, Kampala, Uganda; School of Biological and
Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE,
United Kingdom; ¶University of Lleida, Departament de Produccio Vegetal
I Ciencia Forestal, Avenue Alcalde Rovira Roure 177, E-25198 Lleida,
Spain; and ||School of Biology, University of Newcastle-upon-Tyne,
Newcastle-upon-Tyne NE1 7RU, United Kingdom
Communicated by M. S. Swaminathan, Center for Research on Sustainable
Agricultural and Rural Development, Madras, India, April 12, 2005
(received for review June 18, 2004)
Bacillus thuringiensis (Bt) crystal protein genes encode insecticidal
-endotoxins that are widely used for the development of insect-resistant
crops. In this article, we describe an alternative transgenic strategy
that has the potential to generate broader and more sustainable levels
of resistance against insect pests. Our strategy involves engineering
plants with a fusion protein combining the -endotoxin Cry1Ac with the
galactose-binding domain of the nontoxic ricin B-chain (RB). This
fusion, designated BtRB, provides the toxin with additional, binding
domains, thus increasing the potential number of interactions at the
molecular level in target insects. Transgenic rice and maize plants
engineered to express the fusion protein were significantly more toxic
in insect bioassays than those containing the Bt gene alone. They were
also resistant to a wider range of insects, including important pests
that are not normally susceptible to Bt toxins. The potential impact of
fusion genes such as BtRB in terms of crop improvement, resistance
sustainability, and biosafety is discussed.
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