Plants Generate Their Own Sunscreen

Ultraviolet radiation hits plants as well as humans, but plants can’t reach for a tube of sunscreen.  Too much exposure can damage them; what do they do?  They have a sensor that turns on production of their own brand of sunscreen and spreads it on their skin automatically.
    UV-B rays are the most damaging rays in sunlight.  In Science this week,¹ researchers at the University of Glasgow explained how plants have a protein named UVR8 that normally comes in pairs.  UV-B rays break up the pairs; as single molecules now, UVR8 proteins link up with others named COP1.  This combination signals the nucleus to ramp up production of sunscreen.  The abstract said in jargon,

Absorption of UV-B induces instant monomerization of the photoreceptor and interaction with COP1, the central regulator of light signaling.  Thereby this signaling cascade controlled by UVR8 mediates UV-B photomorphogenic responses securing plant acclimation and thus promotes survival in sunlight.”

Professor Gareth Jenkins explained for University of Glasgow News, “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.”  So it’s not just having UVR8 able to absorb the harmful photons – it’s also a matter of having them link up with other proteins and switch on genes – then having the gene products arrive at the proper destination to give protection quickly.
    Scientists knew plants were able to protect themselves, but didn’t know what photoreceptor was sensitive to UV-B light.  “UVR8 is always present throughout a plant so it can respond immediately to sunlight,” the press release said.

1.  Rizzini…Jenkins, Ulm et al, “Perception of UV-B by the Arabidopsis UVR8 Protein,” Science, 1 April 2011: Vol. 332 no. 6025 pp. 103-106, DOI: 10.1126/science.1200660.

April 1 makes fools of some of us, but plants don’t fool around.  Especially foolish were the brain offerings given to Charlie in the articles.  The press release lit this stick of stinkincense: “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 sunscreen and depositing it in the outer tissues of leaves.”  Would that evolutionists would evolve a way of evolving away evolutionary folly.
    The paper in Science was no better: “Several families of plant photoreceptors have evolved that monitor light ranging from ultraviolet-B (UV-B) to the near infrared and allow optimal adaptation to light.”  Their last sentence lubricated the Darwinian imagination: “This raises the intriguing possibility that, together with the development of an ozone layer in the stratosphere of Earth, the evolution of terrestrial plants may be coincident with the acquisition of the UV-induced responses mediated by the UVR8 UV-B photoreceptor.”  Anything’s possible; pigs could evolve wings and fly coincident with the acquisition of big bad wolves in the neighborhood.  That’s intriguing to imagine, too.
    How long must we put up with this foolishness?  It’s happening 365x24x7, not just on April Fool’s Day.  Turn off the black light and let the sun shine in, under the ozone of critical thinking.