ABSTRACT

A biophysical survey was conducted in 15 cotton-growing districts of Pakistan. Four hundred cotton growers were approached and inquired about the production technology of Bt cotton. Further, 25 strip tests using combo strips (Cry1Ac, Cry2Ab, Vip3Aa and Cp4, EPSPS gene) were performed at each farmer’s field. Out of 10,000 total-tested samples, farmers claimed 9682 samples as Bt and 318 samples as non-Bt. After performing a strip test, 1009 and 87 samples were found false negative and false positive, respectively. Only 53 samples were found positive for Cry2Ab, 214 for EPSPS and none for Vip3Aa gene. Quantification of Cry endotoxin and bioassay studies were performed by taking leaves from upper, middle, and lower canopies, and fruiting parts at approximately 80 days after sowing from 89 varieties. Expression was highly variable among different canopies and fruiting parts. Moreover, Cry endotoxin expression and insect mortality varied significantly among varieties from 0.26 µg g⁻¹ to 3.54 µg g⁻¹ with mortality ranging from 28 to 97%, respectively. Highest Cry1Ac expression (3.54 µg g⁻¹) and insect mortality (97%) were observed for variety FH-142 from DG Khan. Cry endotoxin expression varied significantly across various plant parts, i.e., IUB-13 variety from upper canopy documented 0.34 µg g⁻¹ expression with 37% insect mortality in Layyah to 3.42 µg g⁻¹ expression and 96% insect mortality from DG Khan. Lethal dose, LD95 (2.20 µg g⁻¹) of Cry1Ac endotoxin was optimized for effective control of H. armigera. Our results provided evidence of practical resistance in H. armigera and way forward.

摘要

在巴基斯坦的 15 个棉花种植​​区进行了生物物理调查。走近了 400 名棉农，询问了 Bt 棉花的生产技术。此外，使用组合条（Cry1Ac、Cry2Ab、Vip3Aa和Cp4 、EPSPS基因）在每个农民的田间进行了25 次条带测试。在总共测试的 10,000 个样本中，农民声称 9682 个样本为 Bt，318 个样本为非 Bt。进行条带测试后，分别发现 1009 个和 87 个样本为假阴性和假阳性。仅 53 个样本被发现对Cry2Ab呈阳性，214 个样本对EPSPS呈阳性，而Vip3Aa 则没有基因。Cry 内毒素的定量和生物测定研究是通过从 89 个品种播种后大约 80 天从上、中、下树冠和结果部分取出叶子来进行的。表达在不同冠层和结果部分之间高度可变。此外，Cry 内毒素表达和昆虫死亡率在 0.26 µg g ^-1至 3.54 µg g ^{-1 的}品种之间差异显着，死亡率分别为 28% 至 97%。对于来自 DG Khan 的品种 FH-142，观察到最高的Cry1Ac表达 (3.54 µg g ^-1 ) 和昆虫死亡率 (97%)。Cry 内毒素的表达在植物的不同部位有显着差异，即来自上层冠层的 IUB-13 品种记录为 0.34 µg g ^-1在 Layyah 表达 37% 的昆虫死亡率到 3.42 µg g ^-1表达和 96% 的 DG Khan 昆虫死亡率。Cry1Ac 内毒素的致死剂量 LD95 (2.20 µg g ^-1 ) 为有效控制棉铃虫进行了优化。我们的结果提供了棉铃虫的实际抗性和前进方向的证据。