Plant Communication Through Root Systems

Last week I discussed the relationship between mycorrhizae and plants, and how this relationship benefits plants in communicating with each other. This week I will discuss a journal article called, “Rumor Has It: Relay Communication of Stress Cues in Plants" in which extensive experimentation was performed to test whether plants use there roots to communicate with each other. 


In the study conducted by Falik et al. (2011), the hypothesis was tested that unstressed plants were able to respond to stress cues emitted from their abiotically-stressed neighbors and in turn induce stress responses in additional unstressed plants located nearby. Five Pisum sativum plants were subjected to drought like conditions, they had five neighboring Pisum sativum plants on either side that were under normal ‘unstressed’ conditions. They placed these normal or unstressed plants next to the stressed ones so that they could communicate with each other. On one side the drought induced plants did not share a root system with their neighbor’s (unshared). This meant that they were limited to shoot communication. On the other side the stressed plants shared their rooting volume with the nearest unstressed plant, and all plants shared their rooting volumes with their immediate neighbors (shared), this enabled both root and shoot communication. 


The few Pisum sativum plants that were exposed to drought conditions were checked after fifteen minutes, and as expected there was significant stomatal closure observed. But what was more interesting was that the neighboring unstressed and shared root system plants (shared) showed stomatal closure as well and after an hour all of these plants had closed their stomata. No stomatal closure was observed in the neighboring plants that did not share a root system (unshared) with the stressed plants and were therefore reliant on shoot communication. These results demonstrate that unstressed plants are able to perceive and respond to stress cues emitted by the roots of their drought stressed neighbors, and also relay elicit stress responses in further unstressed plants (Falik et al. 2011).

Further work is underway to study the underlying mechanisms of this new mode of plant communication and its possible adaptive implications for the anticipation of forthcoming abiotic stresses by plants.

WOW how cool is that!!! Keep reading to learn more about this fascinating area of plant biology.

Reference

Falik, O, Mordoch, Y, Quansah, L, Fait, A, Novoplansky, A 2011, 'Rumor Has It...: Relay Communication of Stress Cues in Plant', Public Library of Science, vol. 6,  no. 11, viewed 30/03/2014, http://search.proquest.com.elibrary.jcu.edu.au/docview/1310932339

The Relationship Between Mycorrhizae and Plants

This week I decided to do something a little bit different and incorporate a video into my blog. This is so you can all view an expert’s opinion, and gain some insight into the topic of plant communication. In previous blogs I have been talking about the different mechanisms behind plant communication. This incorporates the relationship between mycorrhizae, and plant roots.  Mycorrhizae and plant roots have a symbiotic relationship in which they both benefit. Mycorrhiza forms fine filaments that spread out in the soil and act as root extensions. These can often absorb more nutrients and water than the plant roots themselves in return the plant supplies sugars synthesized during photosynthesis to the mycorrhizae (Abell 2014). Studies have led to the conclusion that through these mycorrhizae connections and extensions plants can communicate with each other.

This is a brief overview of the relationship between mycorrhizae and plants and how they use these mycorrhizae to communicate with each other. In future blogs I will discuss the specific studies that have been undertaken in order to demonstrate this theory. 

                                          Video- Do trees communicate 2012

If you feel like having a read of on this topic, this is a link to an article posted by BBC called “Fungus network 'plays role in plant communication” which gives a brief overview.  http://www.bbc.com/news/science-environment-22462855

 References

Dr Abell, S 2014, ‘Fungi in restoration’, Lecture note discussed in Restoration Ecology (BZ2480) at James Cook University on Thursday 20^th of March 2014.

Video- Do trees Communicate 2012, http://youtu.be/iSGPNm3bFmQ, UBC Faculty of Forestry

Volatile Signalling Between Plants

In my last post I discussed the underlying theory to plant communication. In this blog I hope to outline a possible signalling mechanisms used in plant communication. It is possible that there are many signalling mechanisms used and all so possible that different plant species use different mechanisms dependent on the situation and environment. The topic has such a vast array of possibilities that makes it difficult to pinpoint one possible mechanism that works in all situations and with all plant.

In their article Baldwin, Kessler and Halitschke (2002) discussed volatile signalling. In which plants are assumed to release volatiles after herbivores attack and it is thought to be done so in a highly regulated fashion. These VOCs (volatile organic compounds) that are release attract herbivorous predators and so act as indirect defences for the plants.

Plants are highly evolved for gas exchange, and have the capacity to release complex arrangements of VOCs into the air. This ability is what fuels the idea that plants communicate though volatiles. Plants compete for resources, and this gives rise to the idea that plants providing information to competitors are unlikely to be selected for in an environment. This therefore suggests that instead of being dubbed plant 'communication' it should rightly be named 'Eavesdropping elms'. Wounding plants releases volatiles; one reason for this is because the vascular tissue of the plant has been damaged in which VOCs are stored. But it has all so been shown that it is a result of de novo synthesis which is the synthesis of complex molecules from simple molecules such as sugars or amino acids.

Balwin, Kessler and Halitschke's (2002) article goes on to then talk about how the testing for this experiment needs be improved, highly regulated and more similar to the natural environmental conditions that the plants endure in order for it to be seen as a viable mechanism for communication between plants.

I hope to have given a brief overview of how is it possible for plants to communicate, or eves drop via volatiles to increase their environmental fitness.

If you wish to read more on this topic, the reference in given below.

Baldwin, I, Kessler, A, Halitschke, R 2002, 'Volatile signaling in plant–plant–herbivore interactions:
what is real?' Current Opinion in Plant Biology, vol. 5, no.2, pp. 351-354

Communication Between Plants

From our general knowledge about plants it is fair to infer that they interact with each other in competition for sunlight, nutrients and water. But whether plants actively communicate with each other, is both a fascinating and stimulating topic in plant ecology.
 

The theory behind communication of plants is that rooted and immobile plants, act to increase their biological fitness in their environment by taking cues from nearby plants that are being negatively affected by herbivores and pathogens. This theory poses many questions, such as; through what mechanism do plants signal to each other? Do all plant species do it? Is there a sense of altruism between plants that is necessary for their survival? Unfortunately there has not been much research into this realm of plant ecology. But Anurag (2000) has recognised that some studies have had success in demonstrating plant communication better than previous attempts. In a experiment conducted by Dolch and Tscharntke (2000). They extensively and accurately studied plant communication whereby they found that; when alder plants (Alnus glutinosa) were manually defoliated, the herbivorous alder beetles (Agelastica alni) distribution increased with further distance from the defoliated tree. From this they concluded, that defoliation of alder plants may trigger interplant resistance transfer to reduce the impacts of herbivores.

There are still many factors within this area of plant ecology that need researching. By delving into other relevant journal articles within this area of study I hope to further the understanding of plant communication in future blogs. 

If you want to read more on this topic refer to the articles in the reference list below.

  

Anurag, A 2000, 'Communication between plants: this time its real', Journal Club, vol. 15, no. 3,  pp. 446. viewed 5 March 2014, http://dx.doi.org.elibrary.jcu.edu.au/10.1016/S0169-5347(00)01987-X

Dolch. R, Tscharntke. T, 2000, 'Defoliation of alders (Alnus glutinosa) affects herbivory by leaf beetles on undamaged neighbours'. Oecologia, Springer-Verlag, vol. 125, no. 4, pp. 504-511. veiwed 7 March 2014, http://dx.doi.org/10.1007/s004420000482