Institut für Biologie, Dahlem Center of Plant Sciences, Ökologie der Pflanzen, Freie Universität Berlin, Berlin, Germany.
PLoS One. 2011;6(11):e27195. doi: 10.1371/journal.pone.0027195. Epub 2011 Nov 14.
Allelopathy, a phenomenon where compounds produced by one plant limit the growth of surrounding plants, is a controversially discussed factor in plant-plant interactions with great significance for plant community structure. Common mycorrhizal networks (CMNs) form belowground networks that interconnect multiple plant species; yet these networks are typically ignored in studies of allelopathy. We tested the hypothesis that CMNs facilitate transport of allelochemicals from supplier to target plants, thereby affecting allelopathic interactions. We analyzed accumulation of a model allelopathic substance, the herbicide imazamox, and two allelopathic thiophenes released from Tagetes tenuifolia roots, by diffusion through soil and CMNs. We also conducted bioassays to determine how the accumulated substances affected plant growth. All compounds accumulated to greater levels in target soils with CMNs as opposed to soils without CMNs. This increased accumulation was associated with reduced growth of target plants in soils with CMNs. Our results show that CMNs support transfer of allelochemicals from supplier to target plants and thus lead to allelochemical accumulation at levels that could not be reached by diffusion through soil alone. We conclude that CMNs expand the bioactive zones of allelochemicals in natural environments, with significant implications for interspecies chemical interactions in plant communities.
化感作用，一种由植物产生的化合物限制周围植物生长的现象，是植物-植物相互作用中一个备受争议的讨论因素，对植物群落结构具有重要意义。常见的菌根网络（CMNs）在地下形成网络，将多个植物物种相互连接；然而，这些网络在化感作用的研究中通常被忽略。我们测试了一个假设，即 CMNs 促进了从供体植物到目标植物的化感物质的运输，从而影响化感相互作用。我们分析了通过土壤和 CMNs 扩散的模型化感物质，除草剂咪草烟，以及从 Tagetes tenuifolia 根系释放的两种化感噻吩的积累。我们还进行了生物测定，以确定积累的物质如何影响植物生长。与没有 CMNs 的土壤相比，所有化合物在有 CMNs 的目标土壤中积累到更高的水平。这种积累的增加与 CMNs 土壤中目标植物生长的减少有关。我们的结果表明，CMNs 支持化感物质从供体植物向目标植物的转移，从而导致化感物质的积累水平无法仅通过土壤扩散达到。我们得出结论，CMNs 扩大了自然环境中化感物质的生物活性区，对植物群落中种间化学相互作用具有重要意义。
