USDA ARS, U.S. Arid Land Agricultural Research Center, Maricopa, AZ, 85138, USA.
Department of Entomology, University of Arizona, Tucson, AZ, 85721, USA.
Sci Rep. 2020 May 14;10(1):7988. doi: 10.1038/s41598-020-64811-w.
Evolution of pest resistance threatens the benefits of crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt). Field populations of the pink bollworm (Pectinophora gossypiella), a global pest of cotton, have evolved practical resistance to transgenic cotton producing Bt toxin Cry2Ab in India, but not in the United States. Previous results show that recessive mutations disrupting an autosomal ATP-binding cassette gene (PgABCA2) are associated with pink bollworm resistance to Cry2Ab in field-selected populations from India and in one lab-selected strain from the United States (Bt4-R2). Here we discovered that an independently derived, lab-selected Cry2Ab-resistant pink bollworm strain from the United States (BX-R) also harbors mutations that disrupt PgABCA2. Premature stop codons introduced by mis-splicing of PgABCA2 pre-mRNA were prevalent in field-selected larvae from India and in both lab-selected strains. The most common mutation in field-selected larvae from India was also detected in both lab-selected strains. Results from interstrain crosses indicate BX-R has at least one additional mechanism of resistance to Cry2Ab that does not involve PgABCA2 and is not completely recessive or autosomal. We conclude that recessive mutations disrupting PgABCA2 are the primary, but not the only, mechanism of resistance to Cry2Ab in pink bollworm.
害虫抗药性的进化威胁到了利用苏云金芽孢杆菌（Bt）生产杀虫蛋白的转基因作物的效益。棉花全球性害虫粉红棉铃虫（Pectinophora gossypiella）的田间种群已经对印度生产 Bt 毒素 Cry2Ab 的转基因棉花产生了实际抗性，但在美国却没有。先前的研究结果表明，破坏常染色体 ATP 结合盒基因（PgABCA2）的隐性突变与印度田间选择群体和美国一个实验室选择的品系（Bt4-R2）中粉红棉铃虫对 Cry2Ab 的抗性有关。在这里，我们发现美国独立获得的、实验室选择的 Cry2Ab 抗性粉红棉铃虫品系（BX-R）也携带有破坏 PgABCA2 的突变。PgABCA2 前体 mRNA 剪接错误导致的提前终止密码子在印度田间选择的幼虫以及两个实验室选择的品系中都很常见。在印度田间选择的幼虫中最常见的突变也在两个实验室选择的品系中被检测到。来自品系间杂交的结果表明，BX-R 对 Cry2Ab 至少有一种额外的抗性机制，该机制不涉及 PgABCA2，并且不完全是隐性或常染色体的。我们得出结论，破坏 PgABCA2 的隐性突变是粉红棉铃虫对 Cry2Ab 产生抗性的主要机制，但不是唯一机制。
