Improving photosynthesis and crop productivity by accelerating recovery from photoprotection
Faster light adaptation improves productivity Crop plants protect themselves from excess sunlight by dissipating some light energy as heat, readjusting their systems when shadier conditions prevail. But the photosynthetic systems do not adapt to fluctuating light conditions as rapidly as a cloud passes overhead, resulting in suboptimal photosynthetic efficiency. Kromdijk et al. sped up the adaptation process by accelerating interconversion of violaxanthin and zeaxanthin in the xanthophyll cycle and by increasing amounts of a photosystem II subunit. Tobacco plants tested with this system showed about 15% greater plant biomass production in natural field conditions. Science, this issue p. 857 Altering the regulation of light harvesting increases photosynthetic efficiency and biomass productivity in crop plants. Crop leaves in full sunlight dissipate damaging excess absorbed light energy as heat. When sunlit leaves are shaded by clouds or other leaves, this protective dissipation continues for many minutes and reduces photosynthesis. Calculations have shown that this could cost field crops up to 20% of their potential yield. Here, we describe the bioengineering of an accelerated response to natural shading events in Nicotiana (tobacco) resulting in increased leaf carbon dioxide uptake and plant dry matter productivity by about 15% in fluctuating light. Because the photoprotective mechanism that has been altered is common to all flowering plants and crops, the findings provide proof of concept for a route to obtaining a sustainable increase in productivity for food crops and a much needed yield jump.
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