Resistance to host conifer chemical defenses by bark beetles

树木对试图以它们为食的食草性昆虫发动化学战。例如，当树皮甲虫攻击一棵树时，树立即开始向树上传播含有毒素的树脂。随着甲虫的攻击继续下去，树往往能够通过制造新的更有毒的树脂化学物质来做出反应，试图杀死甲虫或将它们赶走。然而，甲虫往往会在攻击中获胜，树也会被杀。因为甲虫进化出了能有效解毒树脂化学物质的酶。这些酶中的一些被称为细胞色素P450，任何给定的昆虫物种都可能有许多不同种类的这些酶，每种酶都有助于它对不同的植物化学物质解毒。我研究的目的是发现对树皮甲虫攻击针叶树很重要的细胞色素P450。我打算既识别甲虫产生解毒酶所开启的细胞色素P450基因，又描述酶对树木树脂化学物质解毒的机制。有了这些知识，我的研究就是发现细胞色素P450基因，这些基因是甲虫用来产生解毒酶的，并描述这些酶对树木树脂化学物质解毒的机制也许可以设计出仅抑制某些树皮甲虫体内特定酶的杀虫剂。这种杀虫剂会使甲虫更容易受到寄主树毒素的影响，因此树可以更频繁地与甲虫打赢这场战斗。由于杀虫剂的设计只针对特定物种甲虫中的一种或两种酶，因此它不会对其他重要的森林生物产生影响。此外，更好地了解哪些树脂化学物质足够危险，以至于树皮甲虫会花费相当大的能量来为化合物解毒，这将有助于树木育种者努力培育出更能抵抗树皮甲虫攻击的针叶树。

Trees wage chemical warfare upon the herbivorous insects that try to feed on them.  For instance, when  bark beetles attack a tree, the tree immediately begins to spread resin, which contains toxins, onto them.  As the attack by the beetles continues, the tree is often able to respond by manufacturing new resin chemicals that are even more toxic in an effort to kill the beetles or to drive them out.  Often, however, the beetles prevail in their attack and the tree is killed, because the beetles have evolved enzymes that effectively detoxify the resin chemicals.  Some of these enzymes are called "cytochromes P450" and any given insect species likely has many different varieties of these enzymes, which each help it to detoxify different plant chemicals.  The intent of my research is to discover the cytochromes P450 that are important to bark beetles attacking conifers.  I intend to both identify cytochrome P450 genes that the beetles "turn on" to produce the detoxification enzymes and to characterize the mechanisms by which the enzymes detoxify the tree resin chemicals.  With this knowledge, it might be possible to design pesticides that inhibit specific enzymes in only certain species of bark beetles.  This type of pesticide would make the beetles more susceptible to the host tree toxins, and thus the tree could "win" the battle with the beetles more often. Since the pesticide would be designed to be very specific to just one or two enzymes in a particular species of beetle, it would not have effects on other important forest organisms.  In addition, a better understanding of which resin chemicals are sufficiently dangerous that a bark beetle will expend considerable energy to detoxify the compound will assist tree breeders in their efforts to produce conifers that are more resistant to bark beetle attack.