A controversial science.

Let’s start with a bit of background.

Plants have evolved a variety of ways in which they communicate. Until relatively recently, communication in the plant kingdom has been a controversial topic. In 1983, two significant papers were published that seemingly advanced what we know about the world of plants. In one study it was found that poplar and sugar maple seedlings would pump out anti –herbivore toxins when placed in a chamber with shredded leaves of saplings (Baldwin and Schultz 1983). In another study, it was found that willows increased the production of a chemical defense when their neighbours were being attacked by webworms and caterpillars (Rhoades 1983).

Both studies were under heavy scrutiny by eminent ecologists who pointed out that there could be other explanations for the phenomen. At the time, scientists dabbling in this field faced another problem. During the early 80's the book: The Secret Life of Plants, was attracting criticism for making claims about the plant world.  The book was criticised for being as described by Daniel Chamovitz, ‘”scientifically anemic” (Chamovitz 2012). Skepticism from respected scientists resulted in the research slowing down for a short period. Luckily, scientists such as Ted Farmer ( considered a pioneer in the field) continued on. Today, the evidence is clear – at least on this aspect. Plants can release volatiles to deter herbivores, while other plants can detect these airborne signals and respond by increasing their own chemical defense. (Baluska & Ninkovic 2010).    

Figure 1. Front cover of the contraversial book, The Secret Life of Plants by Peter Tompkins and Christopher Bird. Cover illustration: Alan Aldridge (1973).

    

Since this time, an array of mechanisms of which plants can communicate have been identified. Such methods include territorial root communications, volatile signals that induce defense against herbivores, signals from ovules to mother plants, signals associated with root graft information, as well as male to female signals during pollen competition. These mechanisms assist the plants evolutionary success and accomplishes self/non-self kin recognition. From an evolutionary perspective, if the signalling plant derives a fitness benefit from conveying information to other plants, this signal can be classified as communication. (Baluska & Ninkovic 2010). 

A big question that stands today is; what is the plant trying to achieve? If a plant releases a signal, is it trying to help itself, or its neighbour? If it is trying to help its neighbour what does it get in return? Are these signals unintentionally being eavesdropped by surrounding organisms or are they sent with intent? (Baldwin et al. 2006)  These are some of the questions that will come up in the research we will look at over the next few weeks.

Check out my references for some fascinating reading:

Alderidge, A. 1973. The secret life of plants. Penguin. https://zeppelinruc.files.wordpress.com/2012/11/secret-life-of-plants-book.jpg; retrieved 12/03/2015.
Baldwin, I.T., Halitschke, R., Paschold, A., Von Dahl, C.C., Preston, C.A. 2006. Volatile signaling in plant-plant interactions: “talking trees” in the genomics era. Science,   311:812-815.

Baldwin, I.T., Schultz, J.C.1983. Rapid changes in tree leaf chemistry induced by damage: evidence for communication between plants. Science, 221: 277–279

Baluska, F., Ninkovic, V.2010. Plant communication from an ecological perspective. Springer –Verlag, Berlin Heidelberg. 

Chamovitz, D. 2012. What a plant knows. Griffin Press, Australia.Rhoades, D.F. 1983. Response of alder and willow to attack by tent catepilllars and webworms: evidence for phenomonal sensitivity of willows. American Chemical Society Symposium Series, 208: 55 – 68.