PerspectiveMetabolism

Improving crop yield

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Science  04 Jan 2019:
Vol. 363, Issue 6422, pp. 32-33
DOI: 10.1126/science.aav8979

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Summary

The enzyme ribulose 1,5-bisphosphate carboxylase-oxygenase (RuBisCO) is one of the most abundant proteins on Earth. During photosynthesis, it assimilates atmospheric CO2 into biomass and hence is a major driver of the global carbon cycle. However, the enzyme is catalytically imperfect. It accepts not only CO2 as a substrate, but also O2, which leads to the formation of a toxic byproduct, 2-phosphoglycolate (2-PGlycolate) (1). The metabolic pathway photorespiration detoxifies 2-PGlycolate, and it is essential for performing photosynthesis in an O2-containing atmosphere. Importantly, photorespiration causes a 20 to 50% yield penalty, depending on the environmental conditions and the type of photosynthesis employed (2). Multiple attempts have been undertaken to overcome this yield penalty and thereby increase biomass production in plants, with limited success to date. On page 45 of this issue, South et al. (3) present a synthetic pathway that fully detoxifies 2-PGlycolate inside plant chloroplasts. Transgenic tobacco plants expressing this pathway show strongly enhanced biomass production in field trials, suggesting that this could be used to improve crop yields.