Volatiles play major roles in mediating ecological interactions between soil (micro)organisms and plants. It is well‐established that microbial volatiles can increase root biomass and lateral root formation. To date, however, it is unknown whether microbial volatiles can affect directional root growth. Here, we present a novel method to study belowground volatile‐mediated interactions. As proof‐of‐concept, we designed a root Y‐tube olfactometer, and tested the effects of volatiles from four different soil‐borne fungi on directional growth of Brassica rapa roots in soil. Subsequently, we compared the fungal volatile organic compounds (VOCs) previously profiled with Gas Chromatography–Mass Spectrometry (GC–MS). Using our newly designed setup, we show that directional root growth in soil is differentially affected by fungal volatiles. Roots grew more frequently toward volatiles from the root pathogen Rhizoctonia solani, whereas volatiles from the other three saprophytic fungi did not impact directional root growth. GC–MS profiling showed that six VOCs were exclusively emitted by R. solani. These findings verify that this novel method is suitable to unravel the intriguing chemical cross‐talk between roots and soil‐borne fungi and its impact on root growth.

中文翻译：

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土壤传播真菌的挥发物影响根的定向生长

挥发性物质在介导土壤（微生物）和植物之间的生态相互作用中起主要作用。众所周知，微生物挥发物可以增加根系生物量和侧根形成。然而，迄今为止，尚不清楚微生物挥发物是否会影响定向根的生长。在这里，我们提出了一种新的方法来研究地下挥发物介导的相互作用。作为概念验证，我们设计了根Y型管嗅觉仪，并测试了四种不同土壤传播真菌的挥发物对甘蓝型油菜定向生长的影响根在土壤中。随后，我们比较了以前用气相色谱-质谱法（GC-MS）分析的真菌挥发性有机化合物（VOC）。使用我们新设计的设置，我们表明土壤中根系的定向生长受真菌挥发物的影响不同。根部更容易向根病原体Rhizoctonia solani的挥发物生长，而其他三种腐生真菌的挥发物不会影响定向根的生长。GC-MS分析表明，六种挥发性有机化合物仅由sol。R. solani排放。这些发现证明，该新方法适用于揭示根与土壤传播真菌之间有趣的化学串扰及其对根生长的影响。