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Green Sunscreen

On sunny days, you can stay in the shade or use sunscreen, but what about plants? Learn more on this Moment of Science.

Lush, green rainforest

Photo: ozjimbob (flickr)

Many plants have developed techniques to protect themselves from the hot sun including absorbing less light and releasing antioxidants

Plants and animals need the sun’s energy to survive, but too much sun can harm living things.

Everybody knows the sun can burn your skin, but did you know that the sun can also cause damage to the leaves of plants, similar to sunburn in humans? On sunny days, you can stay in the shade or use sunscreen, but what about plants?

Many plant species do have ways to protect themselves from sun. Under low light conditions, leaves absorb as much light as possible. However, when the light becomes more intense, leaves absorb less of the available light to protect themselves from sunburn. Plant biologists have known for some time that individual leaves of many species respond to light this way. In fact, scientists at the Swedish University of Agricultural Sciences recently found that one plant species provides itself with all over sun protection, a kind of green sunscreen!

When the researchers exposed just a few leaves of this plant to intense light, something strange happened. The entire plant, including the shaded leaves, started producing an antioxidant. Why? The antioxidant acts as a sunscreen, ready to protect the leaves from sunburn.

Here’s how. Too much sun produces very reactive forms of oxygen in plants that can damage the leaves. By reacting with the oxygen, the antioxidant prevents leaf damage.

What’s most amazing about this new research is that even the shaded leaves produced the antioxidant. According to the researchers, light on just a few leaves triggered a chemical messenger to alert the entire plant to get ready for a sunbath!

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