Li Tao, Blande James D
Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio Campus, PO Box 1627, 70211, Kuopio, FI, Finland.
Terrestrial Ecology Section, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen E, DK, Denmark.
J Chem Ecol. 2017 Apr;43(4):327-338. doi: 10.1007/s10886-017-0826-z. Epub 2017 Mar 9.
Plant volatiles play crucial roles in signaling between plants and their associated community members, but their role in within-plant signaling remains largely unexplored, particularly under field conditions. Using a system comprising the hybrid aspen (Populus tremula x tremuloides) and the specialized herbivorous leaf beetle (Phratora laticollis) and, combining field, greenhouse and laboratory experiments, we examined whether local damage triggered systemic responses in undamaged branches that lack vascular connection to the damaged branches, and to what extent this was caused by airborne volatile signals versus internal signals. An experiment tracing dye through the vasculature of saplings revealed no downward movement of the dye from upper to lower branches, suggesting a lack of vascular connectivity among branches. However, we found under both field and laboratory conditions that herbivore feeding on upper branches elicited volatile emissions by undamaged lower branches. Greenhouse experiments manipulating air contact between damaged and undamaged branches showed that systemic induction of volatiles was almost eliminated when air contact was interrupted. Our findings clearly demonstrate that herbivore-induced volatiles overcome vascular constraints and mediate within-plant signaling. Further, we found that volatile signaling led to induction of different classes of volatiles under field and environment controlled conditions, with a weaker response observed in the field. This difference not only reflects the dose- and time-dependent nature of volatile signaling, but also points out that future studies should focus more on field observations to better understand the ecological role of volatile-mediated within-plant signaling.
植物挥发物在植物与其相关群落成员之间的信号传递中发挥着关键作用，但其在植物体内信号传递中的作用在很大程度上仍未得到充分探索，尤其是在田间条件下。我们使用一个由杂交白杨（Populus tremula x tremuloides）和专门的食草叶甲虫（Phratora laticollis）组成的系统，并结合田间、温室和实验室实验，研究了局部损伤是否会在与受损枝条没有维管连接的未受损枝条中引发系统反应，以及这种反应在多大程度上是由空气传播的挥发性信号而非内部信号引起的。一项通过幼树维管系统追踪染料的实验表明，染料没有从上部枝条向下部枝条移动，这表明枝条之间缺乏维管连接。然而，我们发现在田间和实验室条件下，食草动物在上部枝条取食都会引发未受损下部枝条释放挥发性物质。控制受损枝条和未受损枝条之间空气接触的温室实验表明，当空气接触中断时，挥发性物质的系统诱导几乎被消除。我们的研究结果清楚地表明，食草动物诱导的挥发性物质克服了维管限制并介导了植物体内的信号传递。此外，我们发现挥发性信号在田间和环境控制条件下会导致不同类别的挥发性物质的诱导，在田间观察到的反应较弱。这种差异不仅反映了挥发性信号的剂量和时间依赖性本质，还指出未来的研究应更多地关注田间观察，以更好地理解挥发性介导的植物体内信号传递的生态作用。
