The Use of Exudates in Plant Communication

I have talked in previous blogs about how plants use chemical signals or VOCs volatile organic compounds in order to communicate messages to each other through the air. But one of the newer and less researched forms or plant communication are those types in which happen under the ground. Within the rhizosphere which is the densely populated area in the soil in which plant root systems must compete with other organisms for access to nutrients (Bais et al 2004).

So how exactly do plants communicate through this densely populated network? We know that mycorrhizal fungi have an impact on plant communication but other research suggest that root exudates also play are large role in the function of plant communication. Root exudates are the chemicals secreted by root systems into the soil and they are known to perform a multitude of functions. One reason why plants release these exudates is as a defence mechanism against pathogens. Most root secreted compounds belong to the chemical class of phenolics, and it is the terpenoids that have antibacterial and antifungal properties. It has been founds that not only do plant roots release exudates into the rhizosphere but they also they release VOCs when defending themselves against predators, it was previously thought that VOCs where only released above ground by plants (Baetz 2014)

This is just another example of how plants communicate. By releasing these chemicals into the soil from their roots systems they are able to ward off any pathogens and defend themselves. Some exudate chemicals even provide benefit by luring certain microbes to them that they may get an advantage from such as mycorrizae.

References

Baetz U. & Martinoia E. (2014) Root exudates: the hidden part of plant defence, Trends in Plant Science 2. 90-98.

Bais P.H., Park S. W., Weir L. T., Callaway M. R and Vivanco M. J. (2004) How plants communicate using the underground information superhighway. Trends in Plant Science 1. 26-32