The Secret Communication of Plants – Sensing a ‘Good Neighbor’ From A Bad One

basil_Basil Basilico Ocimum basilicum albahaca [image credit - Castielli] cc – by – sa 3-0

Love Thy (Plant) Neighbor – Plants of many varieties utilize different signalling or communicative means to both compete with, and cooperate with, other plant species in their vicinity in order to promote growth or enable defense against mutual pests and pathogens. Such means include touch (physical contact or proximity), aromatic chemicals (“oderants”) and even light (its intensity or lack of same).

But in a recent series of simple and elegant experiments with basil and chili pepper plants, scientists found that, even when these normal signalling modes were blocked, some “alternative signalling channel” persisted, allowing one ‘good neighbor’ species to facilitate growth in the other.

The Experiment

A collaborative research team (Gagliano, Renton) at the University of Western Australia examined whether the presence of a “good neighbor” plant like basil (Ocimum basilicum) could favorably influence the germination of chili pepper (Capsicum annuum) seeds even when known channels of communication were blocked.

The researchers utilized a custom-designed set-up that “prevented above and below-ground contact and blocked chemical and light-mediated signals normally exchanged by plants.”

The Results & Conclusion

The team found that “seed germination was positively enhanced by the presence of a ‘good’ neighbor, 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.”

The researchers propose that this putative “alternative signalling modality” serves the purpose of a “general indicator of the presence of heterospecifics (two or more differing plant species) which consequently enables seeds (in this case, the chili seeds) to sense and identify who their neighbor is — before it activates a more specific or finely-tuned response (such as a defense reaction) that could prove costly to the plant, and/or its neighbor, biologically speaking.
But exactly what this alternative signal is, or could be, remains a mystery (but it’s possible that signals could be mediated via micro or nano-scale sound waves).

The study has been published on the biomedcentral Ecology website, under the title ‘Love thy neighbor: facilitation through an alternative signalling modality in plants’ The scientists that conducted the study were Monica Gagliano (Centre for Evolutionary Biology, School of Animal Biology) and Michael Renton (School of Plant Biology). Both schools are part of the University of Western Australia (Crawley, WA)



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