Why don’t plants get sunburnt?

“How do plants avoid DNA damage? Humans burn in the sun and increase their cancer risk but plants expose their leaves with no effect.”

Sun Flower by aresauburn™, on FlickrIt’s no secret that human beings are vulnerable to UV radiation, which is a known cause of skin cancer. But while we cook like a lobster under the sun, plants just seem to shrug it off. That’s because they’re equipped with a special enzyme called photolyase which can repair DNA damage.

On the molecular level, when UV light hits DNA, it causes some of the bonds that hold DNA together to break. These broken bonds can then form incorrect linkages, or ‘dimers’. In turn, these dimers prevent DNA from replicating properly, potentially leading to a genetic mutation.

Plants, however, nip the issue in the bud using an enzyme called photolyase. The enzyme binds to the damaged DNA site and harnesses energy from sunlight to remove the dimers and re-correct the bonds again.

But plants aren’t unique in this feature. In fact, marsupials, birds, fish, amphibians, bacteria, viruses, and yeast all have it. Most mammals on the other hand, including us, lost the ability to make photolyase some 170 million years ago (blame it on our genes).

Answer by Ansel Oommen

Question from @Winbiology via Twitter

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Article by Ansel Oommen

June 10, 2013

Ansel Oommen is a multimedia artist, poet, and science writer with publishing credits in over six countries. A gardening fanatic, he suffers from a prolific green thumb that threatens to turn his house into a raging jungle. Check out Ansel's tremendous portfolio of art here.

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