Experts reveal why plants don't get sunburn

April 1, 2011

( -- Experts at the University of Glasgow have discovered how plants know when to make their own sunscreen to protect themselves from the harmful rays of the sun. Scientists have speculated for decades that plants must have a 'photoreceptor' for UV-B wavelengths in sunlight, similar to those they use to detect other wavelengths which control other processes, such as triggering when they flower.

UV-B is the most powerful part of the daylight spectrum and is potentially damaging both to humans and plants.

Now, a paper published today in Science, explains how a protein, called UVR8, recognises UV-B light and then switches on changes in a plant’s gene expression needed for it to produce its own sun block.

Plants need sunlight to harvest light energy and so, are constantly exposed to UV-B. However, plants rarely show signs of damage because they have evolved a way of protecting themselves from the sun’s harmful rays by making their own and depositing it in the outer tissues of leaves.

Gareth Jenkins, Professor of Plant Cell and Molecular Biology at the University of Glasgow and co-author on the paper, described the paper’s findings as “groundbreaking”.

“The search for this UV-B photoreceptor has been something of a Holy Grail for plant photobiologists. We have known for decades that plants can sense the presence of UV-B and that this stimulates the production of sunscreen chemicals that protect plants in sunlight, but we didn't know how plants were able to recognise the presence of UV-B. Now we do. We have managed to identify the that does this,” says Prof Jenkins.

The research opens up new directions for understanding how plants respond to UV-B.

In 2005, Prof Jenkins and his team in Glasgow showed that UVR8 orchestrates the changes in gene expression which underpin this production of plant sun block. Since then, they have been studying, with colleagues from the Universities of Freiburg and Geneva, how UVR8 works.

UVR8 is always present throughout a plant so it can respond immediately to sunlight. Normally in plants two molecules of UVR8 associate to form what is called a dimer.

This latest paper shows that UV-B light converts the dimer into single molecules of UVR8. It is this conversion of molecules which has a direct effect on the protein and ultimately the which leads to the production of the plant’s sunscreen.

Prof Jenkins continues: “A key process in plants producing sunscreen is the interaction of UVR8 with another called COP1. This interaction results in UVR8 initiating the necessary gene changes to ensure the plant is protected from sunlight.

“When a plant detects UV-B light this light stimulates the synthesis of sunscreen compounds that are deposited in the outer tissues and absorb UV-B, minimizing any harmful transmittance to cells below.

“This is exactly what our sun creams do. In addition, exposure to UV-B stimulates the production of enzymes that repair any damage to DNA. And lastly, genes are switched on that prevent oxidative damage to cells and help to maintain the photosynthetic machinery in the leaves.”

Scientists at Glasgow work with the Arabidopsis plant because it is excellent for molecular biology and genetics.

Arabidopsis which are made to lack UVR8, to test its function in the laboratory, fail to show protection and hence are very sensitive to UV-B, they die when exposed to levels of UV-B typical of bright .

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1 / 5 (10) Apr 01, 2011
plants rarely show signs of damage because they have evolved a way of protecting themselves from the suns harmful rays by making their own sunscreen and depositing it in the outer tissues of leaves.

It's so easy to just glibly throw this out there to show how informed the speaker is. Question is just how did this ability develop when those plants without such protection would have simply withered and died?

There's usually no indication of precisely how things "evolved" their wonderful abilities/traits/characteristics.

It's all usually just "evolved" over eons of time. Start asking these hard questions and hand-waving and magic becomes the order of the day.

I really wish these researchers would simply leave out any attempt to supply an evolutionary history of what is currently observable, testable, repeatable and just plain out in the open for all to see. The evolutionary nonsense just doesn't add any value to the real science whatsoever. It only panders to the religion.
1.4 / 5 (10) Apr 01, 2011
To further show how absurd the evolutionary story is in this context, consider the following:
A key process in plants producing sunscreen is the interaction of UVR8 with another protein called COP1. This interaction results in UVR8 initiating the necessary gene changes to ensure the plant is protected from sunlight.

...and ...
In addition, exposure to UV-B stimulates the production of enzymes that repair any damage to DNA. And lastly, genes are switched on that prevent oxidative damage to cells and help to maintain the photosynthetic machinery in the leaves.

Firstly , response to signals starts gene modification, i.e. it sets in triggers a specific code sequence to be executed. Then the plant does the most amazing thing - REPAIR. Repair means that the whole mechanism knows about damage and contains a stored repair program to execute. I challenge anyone to show how such a sequence could have arisen randomly. Repair means forethought and insight. Evolution denies such.
4.3 / 5 (7) Apr 01, 2011
kevin, who engineered the fish to live near chernobyl?
5 / 5 (6) Apr 01, 2011
I always find it sad when people attempt to refuse the fact of evolution. Evolution is the most scientifically explored, supported, and well evidenced theory ever. There is more data and information that supports evolution than any other theory in existence.

To deny evolution is to deny reality and science.
5 / 5 (4) Apr 01, 2011
It's funny Kevin, the only 'hand-waving' I ever see in these articles is yours. Every one of your posts could be summed up as 'I don't understand it, so, the magic sky fairy must have done it.'
4.3 / 5 (6) Apr 01, 2011

The part you are not looking at is the reason you do not understand. Nature is a game of chance and statistics. All living things die. What changes is how long they live and how effective they are at reproducing. There are many degrees of failure, but all life ends in failure. The world you see around you is the product of a long line of failures. The species who survive are the ones who are the best at avoiding failure. Drug resistant viruses and poison resistant bugs are an example of how fast a species can adapt to change. We have seen cockroaches become immune to poisons in weeks. Imagine how much they can change in a million years. The key is failure though, rather than success. Most of the living things that have ever existed on this planet do not exist here today.

Almost every species that has ever lived is now extinct. Look around you and you see the lucky few.

You are right that it's extremely unlikely that life will evolve. Most do not.

They die.
3 / 5 (2) Apr 01, 2011
Kevin...u iz soo smrt 'n hav singl hendidly overtrnd sighence thru gr8 lack uf no-ledge. all prayz kevin 'n invizable frend!!

Wow, purposefully misspelling is difficult, but I wanted him to be able to understand it.
5 / 5 (1) Apr 01, 2011
@ kevin

Hello, as a continuation of our earlier debates...

Evolution does not deny such. Indeed Evolution is all about change and orderly change whether in responce to the environment or a specific stimulus. But what IS evolution --- well an easy way to pretend to understand it is something happens and a species changes to adapt to it... this is a naive and simplistic way of looking at evolution. A more mature way is to combine a little darwin into your view point and say --- evolution are those mutations that give a species or subset of a species an advantage over stimuli and continue to be spread in that species through reproduction. Now this is not the best definition - but it begins to address your immediate concerns with the article.

A lot of species have repair mechanism's for cell -- to take an evolutionary veiw these mechanisms were probably present all the way back to single organisms in our past ... as is seen in todays single cell organisms
5 / 5 (2) Apr 01, 2011
(cont )

why did they conpare this plant to Arabidopsis ... well Arabidopsis to plants is like fruit flies or mice to humans -- it was the first plant to be sequenced and we know a lot about it -- and it has a very small genome -- the fact that this plant can repair cells but not stnad UV radiation gives it a reason to be studied and single out which genes it is missing that help plants deal with UV.

Science is about observation, it is not a religion - it is flawed and science knows it is flawed.

Unfortunately people who like science ( notice i did not say scientists ) generally think of science as a religion.

Remember science proves it self wrong all the time and rewrites itself... it are those people that take it too seriously that revere it as a religion. Indeed some of the Christians i admire most are serious scientists ie biologists and mathematians; they do not see the conflict of interest because religion is what you believe, science is how you explain what you do.
5 / 5 (2) Apr 02, 2011
Kevin is either an unusually dedicated and reliable troll or he genuinely believes what he types.

Both options are disturbing.

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