Natures wonders: Plant awareness (Introduction)

by David Turell , Tuesday, January 17, 2017, 23:20 (2865 days ago) @ dhw
edited by David Turell, Tuesday, January 17, 2017, 23:37

Plants can respond to sounds, can sense chemicals in the atmosphere, respond to light other than the process of photosynthesis:

http://www.bbc.com/earth/story/20170109-plants-can-see-hear-and-smell-and-respond

"Plants perceive the world without eyes, ears or brains. Understanding how can teach us a lot about them, and potentially a lot about us as well.

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"To see this, you just need to make a fast movie of a growing plant – then it will behave like an animal," enthuses Olivier Hamant, a plant scientist at the University of Lyon, France.

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"These plants are moving with purpose, which means they must be aware of what is going on around them. "To respond correctly, plants also need sophisticated sensing devices tuned to varying conditions," says Schultz.

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"Appel and Cocroft found that recordings of the munching noises produced by caterpillars caused plants to flood their leaves with chemical defences designed to ward off attackers. "We showed that plants responded to an ecologically-relevant 'sound' with an ecologically-relevant response," says Cocroft.

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"Ecological relevance is key. Consuelo De Moraes of the Swiss Federal Institute of Technology in Zurich, along with collaborators, has shown that as well as being able to hear approaching insects, some plants can either smell them, or else smell volatile signals released by neighbouring plants in response to them.

"More ominously, back in 2006 she demonstrated how a parasitic plant known as the dodder vine sniffs out a potential host. The dodder vine then wriggles through the air, before coiling itself around the luckless host and extracting its nutrients.
Conceptually, there is nothing much distinguishing these plants from us. They smell or hear something and then act accordingly, just as we do.

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"the photoreceptors that plants use to "see", for example, are fairly well-studied – but it is certainly an area that merits further investigation.

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"For their part, Appel and Cocroft are hoping to track down the part or parts of a plant that respond to sound.

"Likely candidates are mechanoreceptor proteins found in all plant cells. These convert micro-deformations of the kind that sound waves can generate as they wash over an object into electrical or chemical signals.

Another ability we share with plants is proprioception: the "sixth sense" that enables (some of) us to touch type, juggle, and generally know where various bits of our body are in space.

"Because this is a sense that is not intrinsically tied with one organ in animals, but rather relies on a feedback loop between mechanoreceptors in muscles and the brain, the comparison with plants is neater. While the molecular details are a little different, plants also have mechanoreceptors that detect changes in their surroundings and respond accordingly.

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"So far, what we know is that in plants it is more to do with microtubules [structural components of the cell], responding to stretch and mechanical deformation."

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"when a caterpillar attacks an Arabidopsis plant, it triggers a wave of electrical activity. The presence of electrical signalling in plants is not a new idea – physiologist John Burdon-Sanderson proposed it as a mechanism for the action of the Venus flytrap as early as 1874 – but what is surprising is the role played by molecules called glutamate receptors.

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"Glutamate is the most important neurotransmitter in our central nervous system, and it plays exactly the same role in plants, except with one crucial difference: plants do not have nervous systems.

"'Molecular biology and genomics tell us that plants and animals are composed of a surprisingly limited set of molecular 'building blocks' that are very much alike," says Fatima Cvrčková,.....Electrical communication has evolved in two distinct ways, each time employing a set of building blocks that presumably pre-dates the split between animals and plants around 1.5 billion years ago.

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"And while many consider terms like "plant intelligence" and "plant neurobiology" to be metaphorical, they have still been met with a lot of criticism, not least from Chamovitz. "Do I think plants are smart? I think plants are complex," he says. Complexity, he says, should not be confused with intelligence. (my bold)

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"For example, despite lacking eyes, plants such as Arabidopsis possess at least 11 types of photoreceptor, compared to our measly four. This means that, in a way, their vision is more complex than ours.

Comment: Plants need these senses. With danger they cannot run and hide. Their reactions are automatic, not intelligent, as stated in the bolded statement above. Since they split off from the original animals, it is not surprising they use the same original proteins. All evolution is based on the same starting proteins.