Controlling Plants with Light: LEDs to Change Plant Growth

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Kevin M. Folta, Interim Chairman and Associate Professor, Horticultural Sciences Department, University of Florida, Gainesville, FL. Image courtesy of the University of Florida.

For much of human history, people have managed plant growth in the same way – take the plant outside, put it in the ground and wait for it to grow. But what if, rather than doing this, we could give a plant managed instructions? In essence we would talk to the plants. Then, not only could we tell plants what to produce and how much to produce but do so by communicating in a language that they can understand.

According to new research, we can get a plant to do exactly what we want by using a vocabulary of commands via light-emitting diodes, or LEDs.

This sounds like science fiction, but it isn’t. At the recent Science Writers 2013 conference in Gainesville, FL, Dr. Kevin M. Folta of the University of Florida showed us his vision of growing plants in the future. In this world, there will be automatic lighting systems and reflective surfaces that use varying colors of light to fine-tune a plant’s nutrition, flavor, texture and many other attributes.

Photoreceptor chemistry lets researchers manage many aspects of a plant’s life and growth can be. Now that inexpensive Light Emitting Diodes (LEDs) are available in many wavelengths, Folta’s lab has found ways to use light to manipulate gene expression and dynamically improve nutrition and flavor, control pests, time of flowering and ripening and slow spoilage.

Plants as Environmentally Modified Organisms (EMOs)

Folta says that all plants have a certain genetic potential determined by their genetic makeup, and that we can change that genetic potential either by selection or genetic modification. What happens to a plant largely depends on its environment and by manipulating this environment we can reach the potential determined by a plant’s genetic blueprint.

Folta describes plants as Environmentally Modified Organisms that are able to adapt to change or express their genetic potential based on the signals they receive in their environment. Instead of manipulating physical variables, such as spacing between plants, Folta seeks to make photomorphogenesis changes – to induce changes in plant growth, quality, texture and flavor by using light.

The phytochrome photoreceptor is a pigment that plants use to detect light and is sensitive to light in the red and far-red region of the visible spectrum. Image by Jmol Development Team.

This idea works because plants have three receptors that respond to different parts of the spectrum; the phytochrome pigment responds to the red part of the spectrum, cryptochrome responds to green and blue light and photropin which responds to blue light and controls plant growth.

The idea of using different colors of light to control plant growth is not new, but to understand why it works, Folta says we must understand that different adaptions in an organism are the result of different genes being expressed. In much the same way a plant grown in darkness grows long and tall as it tries to find light, the same type of plant will grow differently outside when exposed to light. They are both genetically identical but the genes that control growth are switched on or off in response to light.

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