The
majority of terrestrial (land) plants associate with mycorrhizal fungi (
Cairney et al 2000).This association can connect the roots of neighbouring
plants into common mycelium networks (CMN's). We touched on this topic last
week looking at the chemical secretion between plants in response to
drought.However, there are many other uses for these underground highways of
information. In fact, to answer some of your questions, it is thought that 90%
of land plants have co -evolved with fungi in a mutualistic symbiosis. These
mutualisms allow the plants to connect with each other, as well as performing a
range of other functions (Babikova & Johnson et al 2013).
Figure 1. Aphid species attached to plant stem. Photographer: Yongxin zhang (2012).
So
as we have seen, plants can communicate through the air with the release of
volatile compounds in response to herbivory. This type of communication has
been observed between roots as well. It has been observed that insect herbivory
can trigger the release of the volatile methyl salicylate. In the bean plant,
Vicia faba, methyl salicylate production can repell aphids. Not only do they
repell; they also attract aphid enemies!
Such as parasitoids. This particular study demonstrates that plants are not
only able to protect themselves through
CMN cables, but they are directly aiming to communicate and therefore influence
the behaviour of insects (Babikova & Gilbert et al 2013).
References:
Babikova,
Z., Gilbert L., Bruce, T., J., Birkett, M., Caulfield J., C., Woodcock., C.,
Pickett., J., A., Johnson., D. 2013. Underground signals carried through
mycelial networks warm neighbouring plants of aphid attack. Ecology Letters,
Vol 16. 7: 835-843.
Babikova,
Z., Johnson, D., Bruce, T., Pickett, J., Gilbert., L.2013. Underground allies:
How and why do mycelial networks help plants defend themselves? Bioessays, vol
36, 1 - 21-26.
Cairney, J., W., G. 2000. Evolution of mycorrhiza systems. Naturwissenschaften.
87L 467-475.
Zhang, Y. (2012). Aphid species attached to plant stem. http://www.gardeningknowhow.com/plant-problems/pests/insects/homemade-aphid-control.htm; retrieved 02/04/ .
Zhang, Y. (2012). Aphid species attached to plant stem. http://www.gardeningknowhow.com/plant-problems/pests/insects/homemade-aphid-control.htm; retrieved 02/04/ .
This is quite a complex relationship. I was intrigued to learn more about it from the fungi’s perspective, as you only really focus on what the plant gets out of the relationship. How do fungi benefit? If it is a mutualistic relationship, what are the plants giving to the fungi? Did the co-evolution of fungi and plants arise only once (explaining why it is in so many species), or has it evolved independently multiple times?
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