The genetic basis for resistance to bioinsecticides in diamondback moth Plutella xylostella

小菜蛾生物杀虫剂抗性的遗传基础

基本信息

批准号：
BB/E021107/1
负责人：
Chris Jiggins
金额：
$ 46.61万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FE021107%2F1
关键词：
genetic basis resistance bioinsecticides diamondback

项目摘要

Recent years have seen the development of several bio-insecticides, which are often very specific in their mode of action and therefore potentially more environmentally friendly than traditional chemical insecticides. It was even suggested that, due to their biological origin, these insecticides might avoid the evolution of resistance in targeted pest species. Unsurprisingly this has not proven to be the case, and increased agricultural use of two of these insecticides, Bt and Spinosad, has led to the evolution of resistance in the diamondback moth, the most destructive global pest of cruciferous crops. Understanding the mode of action and mechanisms of resistance is crucial for long term, sustainable use of these compounds. Furthermore, although transgenic Bt crops are not available for commercial use in the UK, an understanding of the basis for resistance to existing Bt crop sprays will be vital in assessing the likelihood of resistance to transgenic crops in the future. Surprisingly, despite its global importance in both foliar sprays and transgenic crops, the targets for Bt toxin are far from clear. Here, we aim to characterise the genetic basis of resistance in populations of diamondback moth that have acquired resistance to these insecticides in the field. Both Bt (Cry1Ac toxin) and spinosad resistance are known to involve a single major gene and in both cases we have already identified linked molecular markers. We will target the regions of the genome surrounding these resistance genes with anonymous molecular markers. Then, by means of a large-insert BAC library, we will fully sequence the region surrounding the two resistance genes. In order to identify the resistance gene we will then test candidate genes identified from this region to see whether they are expressed in the larvae and in appropriate tissues such as the midgut, and also whether there are differences in expression between resistant and susceptible populations. Additionally, we will use RNAi knockdown experiments to determine whether there is an effect of reducing the expression of the candidate gene on levels of resistance in susceptible lines. We will also characterise sequence differences, if any, between the resistant and susceptible lines in the gene transcript of the candidate locus. This will allow development of rapid PCR-based methods for detecting resistant alleles in field caught samples that will facilitate field monitoring of the spread of resistance alleles. Identification of insecticides with novel modes of action can play an important role in preventing the evolution of cross resistance in populations of agricultural pests, and novel biopesticides such as Bt and spinosad have played an important role in complementing and/or replacing older chemical insecticides. However the evolution of resistance is inevitable in targeted pests unless measures are taken to combat it. A better understanding of the mechanisms of resistance, and hence the mechanism of action of these compounds will be crucially important in developing novel toxins with distinct modes of action, and in developing strategies for combating resistance in the field.

近年来，几种生物杀菌剂的发展通常在其作用方式上通常非常具体，因此可能比传统的化学杀虫剂更环保。甚至有人建议，由于其生物学来源，这些杀虫剂可能避免靶向害虫物种的抗性演变。毫不奇怪，事实并非如此，这两种这些杀虫剂（BT和Spinosad）增加了农业用途，导致了钻石背蛾的抵抗力的演变，这是十字花科作物中最具破坏性的全球害虫。了解抗药性的作用方式和机制对于长期的可持续使用这些化合物至关重要。此外，尽管在英国不可用转基因BT农作物可用于商业用途，但了解对现有BT农作物喷雾的抗药性的理解对于评估未来耐药性转基因作物的可能性至关重要。令人惊讶的是，尽管在叶面喷雾剂和转基因作物中都具有全球重要性，但BT毒素的靶标远非明显。在这里，我们的目的是表征响尾蛇飞蛾种群中耐药性的遗传基础，后者已经获得了对野外这些杀虫剂的抗性。已知BT（CRY1AC毒素）和SpinoSAD耐药性都涉及一个主要基因，在这两种情况下，我们都已经鉴定出链接的分子标记。我们将用匿名分子标记靶向围绕这些抗性基因的基因组区域。然后，通过大型插入BAC文库，我们将对两个电阻基因周围的区域进行完全测序。为了鉴定抗性基因，我们将测试从该区域鉴定的候选基因，以查看它们是否在幼虫和适当的组织中表达，以及诸如Midgut等适当的组织，以及耐药性和易感人群之间的表达差异。此外，我们将使用RNAi敲低实验来确定是否存在降低候选基因表达对易感线抗性水平的影响。我们还将表征候选基因座基因转录中抗性和易感线之间的序列差异（如果有）。这将允许开发基于PCR的快速方法来检测捕获的样品中的耐药等位基因，以促进电阻等位基因扩散的现场监测。具有新型作用模式的杀虫剂鉴定在防止农业害虫种群中跨耐药性的演变中起着重要作用，而新型的生物农药（例如BT和Spinosad）在补充和/或替代旧化学杀虫剂方面起着重要作用。但是，除非采取措施对抗它，否则在靶向害虫中不可避免地会产生抗性的演变。更好地理解抗药性机制，因此这些化合物的作用机制对于开发具有不同作用模式的新型毒素以及制定策略来打击现场的抗性，至关重要。