Compared to Bollgard-I, the utilization of Cry2Ab protein in Bollgard-II cotton cultivars enhances insect control. Field and laboratory studies demonstrated reduction in the numbers of bollworm-infested terminals, squares, and bolls in Bollgard-II cotton lines when compared to both Bollgard-I and non-Bollgard cotton cultivars. This indicates that the combination of Cry2Ab with Cry1Ac increased the overall expression of proteins. The expression of Cry protein varied across different plant parts, such as leaves, bracts, squares, and bolls. As the season progresses, the expression of Cry protein decreased in these plant parts. Leaves exhibited the highest levels of Cry protein expression, followed by squares, flowers, and bolls. Variation in the expression levels of delta endotoxins in different plant parts was one of the contributing factors to the survival of pest populations on Bt cotton. Using a commercially available QL 96 ELISA plate kit, the concentration of delta endotoxin in various plant parts at different phenological stages was determined in twelve BG-II cotton hybrids, namely Ajeet-155, JKCH-2245, RCH-3863, NCS-866, MRC-7373, JKCH-99, MRC-7387, NCEH-21, ANKR-3324, NCSI-1904, and NCHB 9902. Cry1Ac and Cry2Ab protein levels were determined from samples of flowers and fruiting parts (Rind, locule, seed, locule wall and seed) at 40, 75, 100 and 125 days after sowing (DAS) over two consecutive years 2018–2019 and 2019–2020. Cry1Ac protein content and expression was the highest at 100DAS in locule, seed and rind; followed by rind and locule wall and seed in green bolls at 125 DAS; followed by seed, locule, rind and flowers at 75 DAS; followed by flowers at 40 DAS in all the tested twelve Bollgard-II hybrids. Cry2Ab protein content and expression was the highest at 125DAS in locule wall and seed and rind, followed by seed, locule and rind in green bolls at 100 DAS, followed by seed, locule, rind and flowers at 75 DAS, then by flowers at 40 DAS in all the tested twelve Bollgard-II hybrids. Cry1Ac protein expression was less in comparison with Cry2Ab. The research findings indicate that the locule of BG-II cotton plants exhibited the highest expression levels of Cry1Ac and Cry2Ab proteins, followed by the seeds, rind, locule wall, and flowers. These results provide valuable insights into the distribution of Cry protein expression in different plant parts, which can contribute to a better understanding of insect control in Bt cotton cultivars.

中文翻译：

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不同物候期Bt棉花植株不同部位Cry毒素表达情况

与Bollgard-I 相比，Bollgard-II 棉花品种中Cry2Ab 蛋白的利用增强了昆虫控制能力。田间和实验室研究表明，与 Bollgard-I 和非 Bollgard 棉花品种相比，Bollgard-II 棉花品系中受棉铃虫侵染的末端、棉铃和棉铃的数量有所减少。这表明 Cry2Ab 与 Cry1Ac 的组合增加了蛋白质的总体表达。Cry 蛋白的表达在植物的不同部位有所不同，例如叶、苞片、花铃和棉铃。随着季节的推移，这些植物部位的 Cry 蛋白表达量下降。叶子表现出最高水平的 Cry 蛋白表达，其次是方块、花和棉铃。不同植物部位δ内毒素表达水平的差异是Bt棉花上害虫种群生存的影响因素之一。使用市售的QL 96 ELISA平板试剂盒，测定了12个BG-II棉花杂交种，即Ajeet-155、JKCH-2245、RCH-3863、NCS-866、 MRC-7373、JKCH-99、MRC-7387、NCEH-21、ANKR-3324、NCSI-1904 和 NCHB 9902。Cry1Ac 和 Cry2Ab 蛋白水平是从花和果实部分（果皮、子房室、种子、子房室）样品中测定的。连续两年（2018-2019 年和 2019-2020 年）播种后 40、75、100 和 125 天（DAS）。子房内Cry1Ac蛋白含量和表达量在100DAS时最高，种子和外皮；其次是 125 DAS 下的果皮和子房壁以及绿色棉铃中的种子；其次是种子、子房室、果皮和花（75 DAS）；其次是在所有测试的 12 个 Bollgard-II 杂交品种中，在 40 DAS 处开花。Cry2Ab 蛋白含量和表达量在 125 DAS 时子房壁、种子和果皮中最高，其次是 100 DAS 时绿棉铃中的种子、子房室和果皮，其次是 75 DAS 时的种子、子房室、果皮和花，然后是 40 DAS 时的花。所有测试的 12 辆 Bollgard-II 混合动力车均采用 DAS。与 Cry2Ab 相比，Cry1Ac 蛋白表达较少。研究结果表明，BG-II棉花植株的子房中Cry1Ac和Cry2Ab蛋白的表达水平最高，其次是种子、果皮、子房壁和花。