Plants are better in dealing with too much light than previously thought

Plants are damaged by too much sunlight. Researchers from Wageningen and Lithuania have now discovered the workings of an inner protection system which quickly counters the harmful effects of an overdose of light. The finding can be of importance to future crop yields. 

Green plants collect the sun light in an effective manner. The plant guides the trapped 'packages of light' (photons) to the internal processing unit, the so-called reaction center, where the energy is converted by a number of chemical reactions into electrons and protons required for the production of organic molecules, such as sugar. In bright sunlight the reaction center cannot process the formed electrons and protons quickly enough. This can lead to substantial damage to the plant, because so-called free radicals can cause chemical damage to proteins and lipids causing tissue to die.

Protection mechanisms
To prevent the next package absorbed sunlight from being delivered to the reaction center while the previous package has not been processed, the plants deploys various protection mechanisms in which the absorbed light is partially converted to heat which can cause no further damage.

To deploy the protection the plant activates various enzymes, which last from ten seconds to minutes. In fluctuating light, such as with leaves in the wind, this can lead to precious loss of energy. Researchers in the US showed a year and a half ago how important the activating and deactivating of the protection is. They showed that modified tobacco plants, in which the activating and deactivating process has been sped up significantly, led to a fifteen percent increase of biomass.

Plant switches rapidly
The research team of the Laboratory for Biophysics in Wageningen has now discovered, together with researchers from Lithuania, that an important part of the switching process is much more rapid than was hitherto thought. The turning on does take a few dozen seconds, but when the protection is activated, the system can respond instantaneously to the condition of the reaction center.

Limited loss of energy
If the reaction center is still processing the last package of energy, the newly supplied energy is converted to heat; if the reaction center is available, a much lower percentage is converted to heat and the loss of energy is limited.

The results of photosynthesis research of prof. Van Amerongen show that the current models of photosynthesis are not correct, and that plants process light much more efficiently than previously thought. This finding improves the insights to increase production through photosynthesis. This not only applies to food crops, but also for less obvious plants and other photosynthetic organisms.

It seems that this protection mechanism is much less effective in algae and micro algae. 'Breeding' these organisms to include this mechanism into their photosynthetic processes creates improved possibilities to use these 'crops' for bio-energy and valuable chemical products.

Read more about the research here.

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