Key Laboratory of Plant Immunity and College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
USDA ARS, US Arid Land Agricultural Research Center, Maricopa, AZ, USA.
Pest Manag Sci. 2021 Mar;77(3):1169-1177. doi: 10.1002/ps.6192. Epub 2020 Dec 7.
Transgenic crops producing insecticidal proteins derived from Bacillus thuringiensis (Bt) are used globally to kill key insect pests and provide numerous benefits, including improved pest management, increased profits, reduced insecticide use, and increased biological control. Unfortunately, such benefits are rapidly being lost by the evolution of Bt resistance by pests.
The main strategy to delay resistance relies on the use of non-Bt refuge plants to produce sufficient susceptible insects that mate with rare resistant insects emerging from Bt crops, essentially diluting and/or removing resistance alleles from pest populations. A key assumption for the success of this refuge strategy is that inheritance of resistance is recessive. In China, dominant resistance to Cry1Ac Bt cotton by the cotton bollworm Helicoverpa armigera is increasing and is associated with a mutation in the tetraspanin HaTSPAN1 gene, conferring more than 125-fold resistance. Here, we used amplicon sequencing to test the hypotheses that the HaTSPAN1 mutation either arose from a single event and spread or that the mutation evolved independently several times throughout northern China. From three laboratory strains and 28 field populations sampled from northern China, we identified six resistant and 50 susceptible haplotypes. Phylogenetic analysis indicates that the HaTSPAN1 mutation arose from at least four independent origins and spread to their current distributions.
The results provide valuable information about the evolutionary origins of dominant resistance to Cry1Ac Bt cotton in northern China and offer rationale for the rapid increase in field-evolved resistance in these areas, where the implementation of additional practical resistance management is needed. © 2020 Society of Chemical Industry.
全球范围内使用产生自苏云金芽孢杆菌（Bt）的杀虫蛋白的转基因作物来杀死关键的害虫，并带来诸多益处，包括改善害虫管理、增加利润、减少杀虫剂使用和增加生物防治。不幸的是，害虫对 Bt 的抗性进化正在迅速使这些益处丧失。
延迟抗性的主要策略依赖于使用非 Bt 避难所植物来产生足够多的易感性昆虫，这些昆虫与从 Bt 作物中出现的罕见抗性昆虫交配，从而从害虫种群中稀释和/或去除抗性等位基因。这种避难所策略成功的一个关键假设是抗性的遗传是隐性的。在中国，棉铃虫 Helicoverpa armigera 对 Cry1Ac Bt 棉花的显性抗性正在增加，并且与四跨膜蛋白 HaTSPAN1 基因的突变有关，该突变赋予其超过 125 倍的抗性。在这里，我们使用扩增子测序来检验以下假设：HaTSPAN1 突变要么是由单个事件产生并传播的，要么是在整个中国北方独立进化了多次。从三个实验室菌株和中国北方 28 个田间种群中，我们鉴定了 6 个抗性和 50 个敏感单倍型。系统发育分析表明，HaTSPAN1 突变至少起源于四个独立的起源，并传播到它们目前的分布地。
这些结果提供了关于中国北方对 Cry1Ac Bt 棉花显性抗性的进化起源的有价值的信息，并为这些地区田间进化抗性的快速增加提供了合理的解释，需要在这些地区实施额外的实用抗性管理措施。
