Institute of Arctic Biology, Department of Biology & Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA.
J Chem Ecol. 2010 Apr;36(4):369-77. doi: 10.1007/s10886-010-9763-9. Epub 2010 Mar 31.
We studied the effect of epidermal leaf mining on the leaf chemistry of quaking aspen, Populus tremuloides, during an outbreak of the aspen leaf miner, Phyllocnistis populiella, in the boreal forest of interior Alaska. Phyllocnistis populiella feeds on the epidermal cells of P. tremuloides leaves. Eleven days after the onset of leaf mining, concentrations of the phenolic glycosides tremulacin and salicortin were significantly higher in aspen leaves that had received natural levels of leaf mining than in leaves sprayed with insecticide to reduce mining damage. In a second experiment, we examined the time course of induction in more detail. The levels of foliar phenolic glycosides in naturally mined ramets increased relative to the levels in insecticide-treated ramets on the ninth day following the onset of leaf mining. Induction occurred while some leaf miner larvae were still feeding and when leaves had sustained mining over 5% of the leaf surface. Leaves with extrafloral nectaries (EFNs) had significantly higher constitutive and induced levels of phenolic glycosides than leaves lacking EFNs, but there was no difference in the ability of leaves with and without EFNs to induce phenolic glycosides in response to mining. Previous work showed that the extent of leaf mining damage was negatively related to the total foliar phenolic glycoside concentration, suggesting that phenolic glycosides deter or reduce mining damage. The results presented here demonstrate that induction of phenolic glycosides can be triggered by relatively small amounts of mining damage confined to the epidermal tissue, and that these changes in leaf chemistry occur while a subset of leaf miners are still feeding within the leaf.
我们研究了在阿拉斯加内陆的北方森林中，白杨叶小卷蛾（Phyllocnistis populiella）暴发期间，表皮取食对颤杨（Populus tremuloides）叶片化学物质的影响。白杨叶小卷蛾以颤杨叶片的表皮细胞为食。在表皮取食发生后的第 11 天，接受自然水平的叶片取食的白杨叶片中，酚糖苷 Tremulacin 和 Salicortin 的浓度明显高于用杀虫剂处理以减少取食损伤的叶片。在第二项实验中，我们更详细地研究了诱导的时间进程。在表皮取食发生后的第 9 天，自然取食的小枝叶片中叶片酚糖苷的含量相对于用杀虫剂处理的小枝叶片中的含量增加。在一些叶小卷幼虫仍在取食以及叶片承受超过 5%的取食面积时，诱导就发生了。具有叶泌蜜腺（EFNs）的叶片比没有 EFNs 的叶片具有更高的组成型和诱导型酚糖苷水平，但具有和不具有 EFNs 的叶片在对取食作出酚糖苷诱导反应的能力方面没有差异。先前的工作表明，叶片取食损伤的程度与总叶片酚糖苷浓度呈负相关，这表明酚糖苷可以阻止或减少取食损伤。这里呈现的结果表明，酚糖苷的诱导可以被局限于表皮组织的相对少量的取食损伤触发，并且这些叶片化学变化发生在一小部分叶小卷仍在叶片内取食时。
