Natures wonders: plant memories (Introduction)

by David Turell , Sunday, September 10, 2017, 23:04 (2629 days ago) @ David Turell

New research into plant memories:

DAVID: He knows they appear intelligent. I agree. With provided instructions the outward appearance is the same!

"In the study of the plant kingdom, a slow revolution is underway. Scientists are beginning to understand that plants have abilities, previously unnoticed and unimagined, that we’ve only ever associated with animals. In their own ways, plants can see, smell, feel, hear, and know where they are in the world. One recent study found that clusters of cells in plant embryos act a lot like brain cells and help the embryo to decide when to start growing.

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" biologists have shown that certain plants in certain situations can store information about their experiences and use that information to guide how they grow, develop, or behave. Functionally, at least, they appear to be creating memories. How, when, and why they form these memories might help scientists train plants to face the challenges—poor soil, drought, extreme heat—that are happening with increasing frequency and intensity. But first they have to understand: What does a plant remember? What is better to forget?

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"One of the most well-understood forms of plant memory, for example, is vernalization, in which plants retain an impression of a long period of cold, which helps them determine the right time to produce flowers. These plants grow tall through the fall, brace themselves during winter, and bloom in the longer days of spring—but only if they have a memory of having gone through that winter.

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"Scientists first started talking about “plant memory” explicitly in the 1980s. A team in France, for example, happened upon a type of memory in which a plant recalled a history of damage to a leaf on one side of its stem and therefore dedicated its energy to growing in the other direction. Since then, scientists have found that certain plants can remember experiences of drought and dehydration, cold and heat, excess light, acidic soil, exposure to short-wave radiation, and a simulation of insects eating their leaves. Faced with the same stress again, the plants modify their responses. They might retain more water, become more sensitive to light, or improve their tolerance to salt or cold. In some cases, these memories are even passed down to the next generation,.....We now know that plants are capable of much more than they’re given credit for. They can “hear” vibrations, which might help them recognize insect attacks. They share information by broadcasting chemicals through the air or from their roots. In the study of the memories they form, the next step has been to understand how they do it.

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"In recent years, scientists have realized that the genome alone doesn’t determine an organism’s fate. There’s a whole world of epigenetic activity around DNA that impacts which stretches of code get expressed, or translated into action. Florigen turned out to be a tiny protein, too small for the techniques of Lang’s generation to identify. Even if they had found it, they would have been missing a key to the mystery of what makes biennials flower. Amasino’s generation, on the other hand, finally found the right level of activity—the epigenetic level—to see this process in action.

"For example, the mechanism that controls vernalization and flowering in Arabidopsis thaliana, or thale cress, a plant often used as a model in laboratories, is like a Rube Goldberg device of proteins and gene expression. The plant has a set of genes that create the proteins that cause flowers to form. Before vernalization, the cells are full of a second protein, named FLC, that represses those key, flower-promoting genes. But when the plant is exposed to cold, its cells slow the production of FLC until it stops, and the balance of protein power then changes. The cells start producing more and more flower-promoting proteins, until the plant is ready to burst into bloom.

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"Plants, he points out, have incredible abilities to rebound from stressful conditions. In a paper published this summer, for instance, Crisp and his colleagues found that plants subjected to light stress rebounded rapidly—just think how, with the right care, a neglected houseplant can bounce back from a wilted, brown mess. Scientists have now reported plenty of examples of plant memory formation, but naturally they are less likely to publish results of experiments where plants could potentially form memories but don’t. One of the biggest challenges of the field of study is even identifying whether a plant has formed a memory or not.

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"Even when memories do form, they can fade. Another research group has shown, for example, that a plant might form an epigenetic memory of salt stress and pass it along across generations, but that if the stress fades, so does the memory. A plant that remembers too much might sacrifice healthy growth to be constantly on guard against drought, flood, salt, insects.

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"Everything that lives is a bundle of chemicals and electrical signals in dialogue with the environment in which it exists. A memory, such as of the heat of summer on last year’s beach vacation, is a biochemical marker registered from a set of external inputs. A plant’s epigenetic memory, of the cold of winter months, on a fundamental level, is not so different."

Comment: Research is still early but epigenetic DNA effects must make the memories that are found.