Pauchet Yannick, Wilkinson Paul, van Munster Manuella, Augustin Sylvie, Pauron David, ffrench-Constant Richard H
University of Exeter in Cornwall, Penryn, UK.
Insect Biochem Mol Biol. 2009 May-Jun;39(5-6):403-13. doi: 10.1016/j.ibmb.2009.04.001. Epub 2009 Apr 11.
The insect midgut is the primary target site for Bt-derived insecticides and Bt alternatives. However, despite extensive recent study, the precise role and nature of different Bt receptors remains a subject of considerable debate. This problem is fuelled by a lack of understanding of the genes expressed in the insect midgut and their physiological roles. The poplar leaf beetle, Chrysomela tremulae, is an important model for understanding the mode of action of, and resistance to, coleopteran-specific Bt toxins and currently shows the only known naturally occurring case of resistance to Cry3A toxins. Moreover it belongs to the same family as the corn rootworm, Diabrotica virgifera, an economically important beetle pest and target of hybrid corn expressing Cry3 toxins. Pyrosequencing is a fast and efficient way of defining the transcriptome of specific insect tissues such as the larval midgut. Here we use 454 based pyrosequencing to sample the larval midgut transcriptome of C. tremulae. We identify candidate genes of putative Bt receptors including transcripts encoding cadherin-like proteins, aminopeptidase N and alkaline phosphatase. We also describe a wealth of new transcripts predicting rapidly evolving gene families involved in plant tissue digestion, which have no homologs in the genome of the stored product pest the Red Flour beetle, Tribolium castaneum.
昆虫中肠是Bt衍生杀虫剂和Bt替代物的主要靶标位点。然而，尽管最近进行了广泛研究，但不同Bt受体的确切作用和性质仍是一个备受争议的话题。对昆虫中肠中表达的基因及其生理作用缺乏了解加剧了这一问题。杨树叶甲（Chrysomela tremulae）是理解鞘翅目特异性Bt毒素作用模式及抗性的重要模型，目前它是已知唯一对Cry3A毒素具有天然抗性的案例。此外，它与玉米根萤叶甲（Diabrotica virgifera）属于同一家族，玉米根萤叶甲是一种具有经济重要性的甲虫害虫，也是表达Cry3毒素的杂交玉米的防治对象。焦磷酸测序是定义特定昆虫组织（如幼虫中肠）转录组的一种快速有效的方法。在此，我们使用基于454的焦磷酸测序技术对杨树叶甲幼虫中肠转录组进行采样。我们鉴定了假定的Bt受体的候选基因，包括编码类钙粘蛋白、氨肽酶N和碱性磷酸酶的转录本。我们还描述了大量预测参与植物组织消化的快速进化基因家族的新转录本，这些转录本在所储存产品害虫赤拟谷盗（Tribolium castaneum）的基因组中没有同源物。
