Huang Fangneng, Yu Wenbo, Head Graham P, Niu Ying, Sakuno Caroline, Lin Shucong, Silva Tiago, Patla Bhavana
Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
J Invertebr Pathol. 2025 Feb;208:108237. doi: 10.1016/j.jip.2024.108237. Epub 2024 Nov 17.
Cry2Ab2 is a Bacillus thuringiensis (Bt) protein that has been pyramided with Cry1A.105 in transgenic maize and Cry1Ac in cotton to control some major lepidopteran pests including the corn earworm/bollworm, Helicoverpa zea (Boddie). However, the widespread occurrence of resistance of this pest to the pyramided Cry1A/Cry2A crops in the southern region of the United State has become a threat to the sustainability of the technology. In this study, multiple genetic crosses and backcrosses were developed to characterize the inheritance of Cry2Ab2 resistance in two H. zea populations resistant to the single protein, Cry2Ab2 (RR) and the dual proteins in Bt maize, Cry1A.105/Cry2Ab2 (RR). Diet-overlay bioassays with F1 hybrids from reciprocal crosses between a susceptible and the resistant populations showed that the Cry2Ab2 resistance in both RR and RR was inherited autosomally and non-recessively. Segregation tests in F2 and backcrossed generations indicated that the resistance was likely controlled by more than one locus. The effective dominance levels of the resistance estimated at each of three discriminating concentrations were similar between RR and RR, ranging from incompletely dominant to incompletely recessive. The similar inheritance observed in RR and RR suggests that the Cry2Ab2 resistance is independent from the Cry1A.105 resistance. The non-recessive inheritance of the resistance could be an important factor causing the widespread resistance of this insect to the Cry1A/Cry2A crops in the southern region. Implications of the observed inheritance properties in Bt crop resistance management are discussed.
Cry2Ab2是一种苏云金芽孢杆菌（Bt）蛋白，已与Cry1A.105在转基因玉米中以及与Cry1Ac在棉花中进行了基因叠加，以控制一些主要的鳞翅目害虫，包括玉米穗虫/棉铃虫，即棉铃实夜蛾（Helicoverpa zea (Boddie)）。然而，在美国南部地区，这种害虫对基因叠加的Cry1A/Cry2A作物产生广泛抗性，已对该技术的可持续性构成威胁。在本研究中，通过多次遗传杂交和回交来表征两个棉铃实夜蛾种群中Cry2Ab2抗性的遗传特性，这两个种群分别对单一蛋白Cry2Ab2（RR）以及Bt玉米中的双蛋白Cry1A.105/Cry2Ab2（RR）具有抗性。用敏感种群和抗性种群之间正反交产生的F1杂种进行饲料涂抹生物测定，结果表明RR和RR中Cry2Ab2抗性均为常染色体遗传且非隐性遗传。F2代和回交后代的分离试验表明，该抗性可能由多个基因座控制。在三个鉴别浓度下估计的抗性有效显性水平在RR和RR之间相似，范围从不完全显性到不完全隐性。在RR和RR中观察到的相似遗传现象表明，Cry2Ab2抗性独立于Cry1A.105抗性。抗性的非隐性遗传可能是导致该昆虫在美国南部地区对Cry1A/Cry2A作物产生广泛抗性的一个重要因素。本文讨论了所观察到的遗传特性对Bt作物抗性管理的影响。
