抗粘虫转基因作物的开发策略

秋粘虫（Spodoptera frugiperda）因其惊人的迁徙能力、超强的繁殖速度、广泛的取食来源严重危害着农业生产。尤其是在其原产地美洲大陆，仅巴西每年的防治成本就超过6亿美金。近年来，秋粘虫已开始侵袭非洲大陆，未来数年可能扩散至地中海、亚洲等地，其危害不可估量。

培育Bt转基因作物是防治粘虫的有效手段，相关产品也已上市多年，例如：杜邦先锋与陶氏益农合作开发的表达Cry1Fa2蛋白的转基因玉米TC1507（商品名Herculex™ I）；孟山都公司开发的表达Cry2Ab2和Cry1A.105蛋白的第二代抗虫玉米MON89034（商品名YieldGard™ VT Pro™），都具有很好的粘虫抗性效果。二代抗虫玉米MON89034相比于孟山都开发的第一代抗虫玉米MON810来说，对玉米螟抗性相当，但对秋粘虫和棉铃虫的抗性效果要更好，因此在扩大作物抗虫谱，防治昆虫抗性种群方面具有很大的优势。
Bt蛋白间的交互抗性情况是影响昆虫抗性管理效果的重要因素。最近，美国科学家利用纯化的Bt蛋白，Bt玉米和Bt棉花为材料，系统评估了Cry2Ab2蛋白与Cry1F、Cry1A.105、Cry2Ae、Vip3A几种主要的Bt蛋白对秋粘虫的交互抗性情况。结果表明，Cry2Ab2蛋白与Cry1F、Cry1A.105和Vip3A间无交互抗性，但与Cry2Ae蛋白间有交互抗性。
对于利用基因聚合方式实现秋粘虫抗性治理的产品设计策略来说，该结果提供了很有价值的指导方向。
Pest Manag Sci. 2017 Jun 19.
Cross-resistance to purified Bt proteins, Bt corn and Bt cotton in a Cry2Ab2-corn resistant strain of Spodoptera frugiperda.
Author
Yang F, Kerns DL, Head GP, Price P, Huang F. Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, USA.
Abstract
BACKGROUND:
Gene-pyramiding by combining two or more dissimilar Bt proteins into a crop has been used to delay insect resistance. The durability of gene-pyramiding can be reduced by cross-resistance. Fall armyworm, Spodoptera frugiperda, is a major target pest of the Cry2Ab2 protein used in pyramided Bt corn and cotton. Here, we provide the first experimental evaluation of cross-resistance in S. frugiperda selected with Cry2Ab2 corn to multiple Bt sources including purified Bt proteins, Bt corn and Bt cotton.
RESULTS:
Concentration-response bioassays showed that resistance ratios for Cry2Ab2-resistant (RR) relative to -susceptible (SS) S. frugiperda were -1.4 for Cry1F, 1.2 for Cry1A.105, >26.7 for Cry2Ab2, > 10.0 for Cry2Ae, and -1.1 for Vip3A. Larvae of Cry2Ab2-heterozygous (RS), SS, and RR S. frugiperda were all susceptible to Bt corn and Bt cotton containing Cry1 (Cry1F or Cry1A.105) and/or Vip3A proteins. Pyramided Bt cotton containing Cry1Ac+Cry2Ab2 or Cry1Ab+Cry2Ae were also effective against SS and RS, but not RR.
CONCLUSION:
These findings suggest that Cry2Ab2-corn selected S. frugiperda is not cross-resistant to Cry1F, Cry1A.105, or Vip3A protein, or corn and cotton plants containing these Bt proteins, but it can cause strong cross-resistance to Cry2Ae and Bt crops expressing similar Bt proteins.

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