title: An alternative strategy for sustainable pest resistance in genetically enhanced crops.
abstract: Bacillus thuringiensis (Bt) crystal protein genes encode insecticidal delta-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 delta-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.
authors.affiliation: Scientific and Industrial Research and Development Centre, 1574 Alpes Road, Hatcliff, Harare, Zimbabwe.
authors.forename: Luke
authors.initials: L
authors.lastname: Mehlo
authors.forename: Daphrose
authors.initials: D
authors.lastname: Gahakwa
authors.forename: Pham Trung
authors.initials: PT
authors.lastname: Nghia
authors.forename: Nguyen Thi
authors.initials: NT
authors.lastname: Loc
authors.forename: Teresa
authors.initials: T
authors.lastname: Capell
authors.forename: John A
authors.initials: JA
authors.lastname: Gatehouse
authors.forename: Angharad M R
authors.initials: AM
authors.lastname: Gatehouse
authors.forename: Paul
authors.initials: P
authors.lastname: Christou
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D015139:Blotting, Southern; D015153:Blotting, Western; D017931:DNA Primers; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism*; D005818:Genetic Engineering / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006460:Hemolysin Proteins; D007313:Insecta; D016297:Mutagenesis, Site-Directed; D012275:Oryza; D010572:Pest Control, Biological / Q000379:methods*; D030821:Plants, Genetically Modified / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism*; D012276:Ricin / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic; D003313:Zea mays
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D017931:DNA Primers; D004731:Endotoxins; D006460:Hemolysin Proteins; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D012276:Ricin