Plants are in something of a catch-22 when it comes to sunlight, says Stuart Blackman.
On the one hand, they need to soak it up to fuel the production of sugar by photosynthesis; on the other this renders them highly vulnerable to ultraviolet wavelengths in the sun’s rays which are harmful to all living organisms, particularly through the damage it inflicts on DNA.
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So how do plants protect themselves from UV rays?
Plants cannot move into the shade when they’ve had enough sun. Nor can they use biological sunscreens, because this would hamper photosynthesis.
Instead, plants put their energies into repair rather than prevention. UV light activates specialised molecules within plant tissues that initiate a cascade of biochemical reactions leading to the deployment of enzymes that stitch broken strands of DNA back together.
The precise mechanisms are not yet fully understood, but might one day yield new methods for protecting crops – and even perhaps ourselves – against the harmful effects of excessive sun.
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