Social networking in plants: biodiversity as a selective force for inter-plant signalling

现在有明确的证据，主要是来自实验室的实验，植物发出的信号，昆虫植食性，检测到的邻近植物。然而，植物间的信号传导在自然界中的生态和进化过程的意义是未经测试的。最近令人兴奋的发现表明，植物到植物的信号传导通过共同的菌根网络（CMN）发生。菌根真菌在世界上至少80%的植物物种的根部形成共生关系，它们经常同时连接单个植物，从而形成CMN。在自然界中，群落中通过CMN进行植物间信号传导的成本和收益的结果可能受到以下因素的影响：i）与植物物种和食草动物摄食类型（即，它是韧皮部吸吮昆虫还是咀嚼昆虫）相关的信号的特异性（以及植物对信号的响应），ii）菌根真菌物种多样性，以及iii）食草昆虫的专业化程度。在这个大胆的建议，我们测试的假设，CMN为基础的信号和接收器植物的信号的反应是依赖于摄食公会和宿主特异性的昆虫草食动物。此外，由于许多菌根真菌表现出主机的喜好，我们还假设，更大的菌根真菌多样性将导致更多的斑块状真菌网络，因此减少了受体植物的比例，在社区中的受侵染的植物。此外，真菌可能不太可能将警告信号传递给窝藏竞争真菌的植物，而不是只由自己定殖的植物。我们预测，这也将导致菌根真菌的多样性减少的比例接收植物接收或响应信号的植物受到攻击。最后，我们预测，有成本的接收器响应信号，也影响菌根真菌的功能，但总体上有净健身效益的植物。我们的多学科项目建立在过去和当前NERC资助的研究基础上，将导致对植物和真菌生物多样性如何塑造植物间信号传导，群落动态和自然界中的多营养相互作用的理解发生重大变化。

There is now unequivocal evidence, mainly from laboratory experiments, that plants emit signals of insect herbivory that are detected by neighbouring plants. However, the significance of inter-plant signalling for ecological and evolutionary processes in nature is untested. Recent exciting findings have shown that plant to plant signalling occurs via common mycorrhizal networks (CMNs). Mycorrhizal fungi form symbiotic relations on the roots of at least 80% of the world's plant species, and they frequently connect individual plants simultaneously, thus forming a CMN. In nature, the consequences of the costs and benefits of inter-plant signalling via CMNs in communities are likely affected by i) the specificity of the signals (and the plant's response to the signals) in relation to plant species and herbivore feeding type (i.e. whether it is a phloem sucking insect or a chewing insect), ii) mycorrhizal fungal species diversity, and iii) the degree of specialisation of insect herbivores. In this adventurous proposal, we test the hypotheses that CMN-based signals and the receiver plant's response to signals is dependent on the feeding guild and host specificity of the insect herbivore. Moreover, because many mycorrhizal fungi exhibit host preferences, we also hypothesise that greater mycorrhizal fungal diversity will lead to more patchy fungal networks and therefore decrease the proportion of receiver plants that respond to infested plants in the community. In addition, fungi may be less likely to pass warning signals to plants that harbour competing fungi than to plants that are colonised only by themselves. We predict that this would also result in mycorrhizal fungal diversity decreasing the proportion of receiver plants receiving or responding to signals from plants under attack. Finally, we predict that there are costs to receivers in responding to signals that also impact the functioning of mycorrhizal fungi, but overall there is net fitness benefit to the plants. Our multidisciplinary project builds on past and current NERC funded research and will lead to a major step-change in understanding of how plant and fungal biodiversity shapes inter-plant signalling, community dynamics and multi-trophic interactions in nature.