Mehlo Luke, Gahakwa Daphrose, Nghia Pham Trung, Loc Nguyen Thi, Capell Teresa, Gatehouse John A, Gatehouse Angharad M R, Christou Paul
Scientific and Industrial Research and Development Centre, 1574 Alpes Road, Hatcliff, Harare, Zimbabwe.
Proc Natl Acad Sci U S A. 2005 May 31;102(22):7812-6. doi: 10.1073/pnas.0502871102. Epub 2005 May 20.
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.
苏云金芽孢杆菌（Bt）晶体蛋白基因编码的杀虫δ-内毒素被广泛用于抗虫作物的培育。在本文中，我们描述了一种替代转基因策略，该策略有可能产生更广泛、更可持续的抗虫害能力。我们的策略是构建一种融合蛋白的植物，该融合蛋白将δ-内毒素Cry1Ac与无毒蓖麻毒素B链（RB）的半乳糖结合结构域结合在一起。这种融合蛋白命名为BtRB，为毒素提供了额外的结合结构域，从而增加了在目标昆虫分子水平上相互作用的潜在数量。经基因工程改造以表达融合蛋白的转基因水稻和玉米植株在昆虫生物测定中比仅含有Bt基因的植株毒性显著更强。它们还对更广泛的昆虫具有抗性，包括通常对Bt毒素不敏感的重要害虫。本文还讨论了诸如BtRB等融合基因在作物改良、抗性可持续性和生物安全性方面的潜在影响。
