Morton R L, Schroeder H E, Bateman K S, Chrispeels M J, Armstrong E, Higgins T J
Commonwealth Scientific and Industrial Research Organization Plant Industry, GPO Box 1600, Canberra ACT 2601, Australia.
Proc Natl Acad Sci U S A. 2000 Apr 11;97(8):3820-5. doi: 10.1073/pnas.070054597.
Two alpha-amylase inhibitors, called alphaAI-1 and alphaAI-2, that share 78% amino acid sequence identity and have a differential specificity toward mammalian and insect alpha-amylases are present in different accessions of the common bean (Phaseolus vulgaris). Using greenhouse-grown transgenic peas (Pisum sativum), we have shown previously that expression of alphaAI-1 in pea seeds can provide complete protection against the pea weevil (Bruchus pisorum). Here, we report that alphaAI-1 also protects peas from the weevil under field conditions. The high degree of protection is explained by our finding that alphaAI-1 inhibits pea bruchid alpha-amylase by 80% over a broad pH range (pH 4.5-6.5). alphaAI-2, on the other hand, is a much less effective inhibitor of pea bruchid alpha-amylase, inhibiting the enzyme by only 40%, and only in the pH 4.0-4.5 range. Nevertheless, this inhibitor was still partially effective in protecting field-grown transgenic peas against pea weevils. The primary effect of alphaAI-2 appeared to be a delay in the maturation of the larvae. This contrasts with the effect of alphaAI-1, which results in larval mortality at the first or second instar. These results are discussed in relationship to the use of amylase inhibitors with different specificities to bring about protection of crops from their insect pests or to decrease insect pest populations below the economic injury level.
普通菜豆（Phaseolus vulgaris）的不同种质中存在两种α-淀粉酶抑制剂，即αAI-1和αAI-2，它们的氨基酸序列一致性为78%，对哺乳动物和昆虫的α-淀粉酶具有不同的特异性。我们之前利用温室种植的转基因豌豆（Pisum sativum）证明，αAI-1在豌豆种子中的表达能够为豌豆象鼻虫（Bruchus pisorum）提供完全保护。在此，我们报告αAI-1在田间条件下也能保护豌豆免受象鼻虫侵害。高度的保护作用可由我们的发现来解释，即αAI-1在较宽的pH范围（pH 4.5 - 6.5）内可抑制豌豆象鼻虫α-淀粉酶80%的活性。另一方面，αAI-2对豌豆象鼻虫α-淀粉酶的抑制效果要差得多，仅能在pH 4.0 - 4.5范围内抑制该酶40%的活性。然而，这种抑制剂在保护田间种植的转基因豌豆免受豌豆象鼻虫侵害方面仍有部分效果。αAI-2的主要作用似乎是延迟幼虫的成熟。这与αAI-1的作用形成对比，αAI-1会导致幼虫在一龄或二龄时死亡。我们结合使用具有不同特异性的淀粉酶抑制剂来保护作物免受害虫侵害或将害虫种群数量降低至经济损害水平以下这一情况，对这些结果进行了讨论。
