Comm-1 Informative Speech - final draft
I. Intro
A. attention getter
"Imagine, if you will, a sun drenched meadow, seemingly peaceful and full of tall grass
and blooming wildflowers. All is quite except for the rustling of leaves in the wind and
the low hum of dragonflies and foraging bees. However, this placid exterior hides a fierce
conflict that fills the air with silent battle cries, articulated in a language of chemical
signals."
B. Thesis Today I'd like to talk to you about these chemical signals and the way plants
use them to communicate with one another.
C. Ethos As a student of biology and a landscaper I am very interested in the
development of this relatively new field of plant science.
D. Kairos We can all benefit from a greater understanding of this subject
1. the development of this field can have drastic implications on our
understanding of the lives of plants.
2. Even if you are not that interested in the more technical aspect of this subject I
hope you will find it interesting, like I have, to shift your perspective and view
plants not as passive objects but as dynamic life forms that are actively
responding to the world around them.
E. Preview
1. I will give two examples of the way plants communicate
a. Communication through airborne organic compounds
b. and communication through root-to-root contact
2. I will also be describing some of the key experiments that lead to the discovery
of these two modes of communication.
II. Body
A. Airborne Communication
1.When a plant is dealt damage, often by a pest such as a caterpillar, a chemical
response is induced. This includes the release of insecticidal compounds.
a. Make the plant unattractive to insects
b. attract natural predators
2. explanation of studies
a.(Nanjing Forestry University 2012) poplar seedlings isolated in a
chamber. defense-related enzymes were as much as double compared to
control
b.(In the minds of plants 2009, prof Van Hoven - biologist) during South
African drought Acacia trees produced lethal levels of Tannins (4X
normal). Resulting in Kudu die off. Ethylene as (VOC)
3. plants can communicate with one another through airborne chemical signals
called volatile organic compounds
a. What is a volatile organic compound (VOC)?
i. a molecule that has a high vapor pressure and can therefore
evaporate easily.
ii. usually released through the stomata (10 micrometers or 1
millionth of a meter). Used for gas exchange (CO2 + H20) as well
as water vapor.
4. Contradiction in helping potential competitors. Natural selection often rewards
selfish behaviors.
a. airborne signals move faster than internal communication, co-ordinate a
systemic response.
b. more like eavesdropping than warning calls
c. communication is more effective with close genetic relatives. (Ecology
Letters article 2014)
Transition- now that I have discussed airborne communication I would like to talk about
how plants communicate underground
B. In a 2012 study published in the journal: Annals of Botany an experiment was
conducted to test if plants could pick up on cues released by neighboring plants,
specifically cues related to drought stress.
1. experiment set up
-Tie back to Stomata, response to drought stress
2. result: unstressed neighbors closed their stomata by 13–30% compared with
control.
a. "As stated in the article: "Although lacking any elaborate informationprocessing abilities, plants are able to perceive and communicate
environmental information, which may significantly affect their
performance and fitness"
b. in other words plants must be able to respond to current environmental
conditions as well as predict and prepare for future conditions
3.The roots of most plants are surrounded by beneficial fungi called mycorrhizae
a. the beneficial relationship between plants and fungi
i.80% of terrestrial plants establish mutualistic mycorrhizae
ii. allows the exchange of water and nutrients for carbohydrates
iii. denies harmful fungi/bacteria access to plant's roots.
b. can also be a potential vector/avenue for plant-plant communication
i. example: increased resistance to pathogens and greater immune
response between neighboring tomato plants. (2010 study, Plos
One scientific journal)
ii. messages prop. move more quickly in the hyphal networks (15.5
cm/d)
iii. "One can argue that the CMNs may induce systemic defense in
ecosystems, minimizing disease occurrence and severity of damage
in plant communities."
III. Conclusion
Review: Through research conducted in both the field and the laboratory it has been established
that plants are capable of sophisticated communication, both through the air and underground.
"the next time you find yourself in a garden or on a hike take a second to think about all the
things going on that you can't see, the messages being send and received, the battles being waged
complete with espionage, alliances and life or death stakes. The more we learn about plants the
more we discover how dynamic and adaptable they are, and I believe the most exciting
discoveries are yet to come.
References
Karban, Richard. "Plant Behaviour And Communication." Ecology Letters 11.7 (2008):
727-739. Academic Search Complete. Web. 29 June 2015.
Song YY, Zeng RS, Xu JF, Li J, Shen X, Yihdego WG (2010) Interplant Communication
of Tomato Plants through Underground Common Mycorrhizal Networks. PLoS ONE
5(10): e13324. doi:10.1371/journal.pone.0013324
Karban, Richard, Louie H. Yang, and Kyle F. Edwards. "Volatile Communication
Between Plants That Affects Herbivory: A Meta-Analysis." Ecology Letters 17.1 (2014):
44-52. Academic Search Complete. Web. 29 June 2015.
In the Minds of Plants. Prod. Jacques Mitsch. Gedeon Productions, 2009. YouTube.
Falik, Omer, et al. "Plant Responsiveness To Root–Root Communication Of Stress
Cues." Annals Of Botany 110.2 (2012): 271-280. Academic Search Complete. Web. 30
June 2015.
Song YY, Zeng RS, Xu JF, Li J, Shen X, Yihdego WG (2010) Interplant Communication
of Tomato Plants through Underground Common Mycorrhizal Networks. PLoS ONE
5(10): e13324. doi:10.1371/journal.pone.0013324