Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, WA 6009, Australia.
BMC Ecol. 2013 May 7;13:19. doi: 10.1186/1472-6785-13-19.
Both competitive and facilitative interactions between species play a fundamental role in shaping natural communities. A recent study showed that competitive interactions between plants can be mediated by some alternative signalling channel, extending beyond those channels studied so far (i.e. chemicals, contact and light). Here, we tested whether such alternative pathway also enables facilitative interactions between neighbouring plant species. Specifically, we examined whether the presence of a 'good' neighbouring plant like basil positively influenced the germination of chilli seeds when all known signals were blocked. For this purpose, we used a custom-designed experimental set-up that prevented above- and below-ground contact and blocked chemical and light-mediated signals normally exchange by plants.
We found that seed germination was positively enhanced by the presence of a 'good' neighbour, even when the known signalling modalities were blocked, indicating that light, touch or chemical signals may not be indispensible for different plant species to sense each other's presence.
We propose that this alternative signalling modality operates as a general indicator of the presence of heterospecifics, enabling seeds to detect and identify a neighbour prior to engaging in a more finely-tuned, but potentially more costly, response.
物种间的竞争和促进相互作用在塑造自然群落方面起着至关重要的作用。最近的一项研究表明，植物之间的竞争相互作用可以通过一些替代信号通道来调节，这些通道超出了迄今为止研究的通道（即化学物质、接触和光）。在这里，我们测试了这种替代途径是否也能使相邻植物物种之间产生促进相互作用。具体来说，我们研究了当所有已知信号都被阻断时，一种像罗勒这样的“好”邻接植物的存在是否会对辣椒种子的萌发产生积极影响。为此，我们使用了一种定制的实验装置，该装置可以防止地上和地下的接触，并阻断植物通常交换的化学和光介导的信号。
我们发现，即使阻断了已知的信号模式，种子的萌发也会被“好”邻居的存在所促进，这表明光、触摸或化学信号可能不是不同植物物种相互感知所必需的。
我们提出，这种替代信号模式是异质种存在的一般指示物，使种子能够在进行更精细、但潜在成本更高的反应之前，检测和识别邻居。
