[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[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.




--------------------------------------------------------------------------------

********************************************************
To unsubscribe from SANET-MG:
1- Visit http://lists.sare.org/archives/sanet-mg.html to unsubscribe or;
2- Send a message to <listserv@sare.org> from the address subscribed to the list. Type "unsubscribe sanet-mg" in the body of the message.

Visit the SANET-MG archives at: http://lists.sare.org/archives/sanet-mg.html
For more information on grants and other resources available through the SARE program, please visit http://www.sare.org.