Combatting insect pests in major Brazilian Cropping Systems through novel Biotech Approaches

通过新颖的生物技术方法防治巴西主要种植系统的害虫

基本信息

批准号：
BB/R022704/1
负责人：
Angharad Gatehouse
金额：
$ 10.28万
依托单位：
Newcastle University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FR022704%2F1
关键词：
Combatting insect pests major Brazilian

项目摘要

Crop production is the main driver of the Brazilian economy, both for the home-market and for export, with an estimated harvest of 232 million tons of grains and 1.48 million tons of cotton for 2016/2017. However, productivity is severely constrained: (i) as a direct result of the development of resistance in insect pest populations to current control methods, and consequently (ii) by lack of effective control measures and implementation of IPM (Integrated Pest Management) strategies. This proposal seeks to address these major constraints on agricultural productivity through the development of novel, efficacious and safe biopesticides, which can be used as part of an IPM system. For Phase 1 of the project two target insect pests have been selected for study, the native species Spodoptera frugiperda (armyworm), and an invasive pest species, Helicoverpa armigera (cotton bollworm). These species are highly polyphagous and are not only major pests of soybean, but also of other crops important to the Brazilian economy, including maize and cotton, causing an estimated damage of R$ 2.5 billion in the absence of effective crop protection measures. Both pest species have evolved high levels of resistance to synthetic pesticides previously used for their control and are now evolving resistance to Bt-expressing transgenic crops. Our overall strategy is two-fold: (i) to develop highly effective and safe biopesticides and; (ii) to better understand the bases of resistance to currently deployed pest-control strategies with a view to mitigating/controlling these effects in the future. For pest control, we will use RNA interference-based technology to inactivate key genes both in the pest insect itself, and to target microbial symbionts which are critical to insect development and survival. This technology has the potential to be highly specific, reducing/eliminating potential non-target effects seen with the use of synthetic pesticides. Initially we will target the voltage-gated ion channels (VGICs), which are known targets for many synthetic chemistries. In parallel, we will design and produce novel biopesticides using species-specific dsRNAs against targets in the two pests selected by in silico approaches for preliminary toxicity testing. In Phase 1 we will also generate metatranscriptomic data of gut associated microbials of the target insects. These data will be used to design novel biopesticides which affect obligate insect symbionts, using antisense gene regulators targeted to essential genes in symbionts, as 'proof of concept'. To address pesticide resistance, we will also use in silico approaches to identify suitable molecular targets in selected insect pests with known resistance to conventional pesticides; we will test their sensitivity to dsRNA targeted to the VGICs compared to pesticide-sensitive strains. In Phase 2 of the project, we will extend the pest range to include a major virus vector, whitefly (Bemisia tabaci). We will also investigate the potential of using symbionts to deliver the dsRNA targeted to the insect pests (paratransgenesis), as an alternative to targeting symbionts. To extend work on pesticide resistance, recent evidence from the consortium has shown that insecticide-resistant strains of S. frugiperda carry insecticide-degrading bacteria in their gut microbiota, which can contribute to the evolution of resistance. As a 'proof of concept' we will target these microbes using RNAi, to determine whether removing them restores pesticide-susceptibility in this major crop pest. A limitation of using RNAi to control insect pests relates to the sensitivity of the dsRNA to nucleases within the insect gut. We have recently demonstrated that chimeric protein PTD-DRBD combined with dsRNA forms a ribonucleoprotein particle, which is more stable to nucleases, leading to greater gene knockdown and greater toxicity to the insect. We therefore propose to compare the efficacy of the modified dsRNA to the native dsRNA.

农作物生产是巴西经济的主要驱动力，无论是国内市场还是出口，预计 2016/2017 年谷物产量为 2.32 亿吨，棉花产量为 148 万吨。然而，生产力受到严重限制：(i) 害虫种群对当前控制方法产生抗药性的直接结果，以及 (ii) 缺乏有效的控制措施和 IPM（害虫综合治理）战略的实施。该提案旨在通过开发新型、有效和安全的生物农药来解决这些对农业生产力的主要限制，这些生物农药可用作病虫害综合治理系统的一部分。该项目的第一阶段选择了两种目标害虫进行研究，即本地物种草地贪夜蛾（粘虫）和入侵性害虫物种棉铃虫。这些物种具有高度杂食性，不仅是大豆的主要害虫，也是对巴西经济重要的其他作物（包括玉米和棉花）的主要害虫，在缺乏有效作物保护措施的情况下，估计造成 25 亿雷亚尔的损失。这两种害虫都对以前用于控制的合成农药产生了高水平的抗性，现在又对表达 Bt 的转基因作物产生了抗性。我们的总体战略有两个：(i) 开发高效、安全的生物农药； (ii) 更好地了解对当前部署的害虫控制策略的抵抗力基础，以期在未来减轻/控制这些影响。对于害虫防治，我们将使用基于RNA干扰的技术来灭活害虫本身的关键基因，并针对对昆虫发育和生存至关重要的微生物共生体。该技术具有高度特异性的潜力，可以减少/消除使用合成农药时出现的潜在非目标效应。最初，我们将针对电压门控离子通道（VGIC），这是许多合成化学的已知目标。与此同时，我们将使用物种特异性 dsRNA 设计和生产新型生物农药，针对通过计算机方法选择进行初步毒性测试的两种害虫的靶标。在第一阶段，我们还将生成目标昆虫肠道相关微生物的宏转录组数据。这些数据将用于设计影响专性昆虫共生体的新型生物农药，使用针对共生体中必需基因的反义基因调节剂作为“概念证明”。为了解决农药抗性问题，我们还将使用计算机方法来确定对传统农药具有已知抗性的选定害虫的合适分子靶点；我们将测试它们对针对 VGIC 的 dsRNA 的敏感性，并与农药敏感菌株进行比较。在该项目的第二阶段，我们将扩大害虫范围，将主要病毒载体烟粉虱（Bemisia tabaci）纳入其中。我们还将研究使用共生体传递针对害虫的 dsRNA（平行转基因）的潜力，作为针对共生体的替代方案。为了扩大杀虫剂抗性方面的研究，该联盟最近的证据表明，抗杀虫剂的草地贪夜蛾菌株的肠道微生物群中携带杀虫剂降解细菌，这可能有助于抗药性的进化。作为“概念验证”，我们将使用 RNAi 来瞄准这些微生物，以确定去除它们是否可以恢复这种主要农作物害虫的农药敏感性。使用 RNAi 控制害虫的局限性与 dsRNA 对昆虫肠道内核酸酶的敏感性有关。我们最近证明，嵌合蛋白PTD-DRBD与dsRNA结合形成核糖核蛋白颗粒，该颗粒对核酸酶更稳定，从而导致更大的基因敲低和对昆虫的更大毒性。因此，我们建议将修饰的 dsRNA 与天然 dsRNA 的功效进行比较。