Shortening the Photorespiration Pathway


Photorespiration is a type of metabolic reaction which takes place in plants - they take up oxygen in the light and give out some carbon dioxide, contrary to photosynthesis.  It is a highly wasteful pathway (due to being extremely energy-expensive) that decreases the yield of plants hugely (occurs when the Calvin Cycle enzyme rubisco acts on oxygen rather than carbon dioxide, using up fixed carbon). If a plant photorespires, instead of photosynthesising, its yield can be severely reduced by 20% (in wheat) and 36% (in soybeans)!



Rubisco, or in full, ribulose-1,5-biphosphate carboxylase is an enzyme present in chloroplasts which is involved in photosynthesis. This enzyme, as well as energy from the sun is used to turn carbon dioxide and water into sugar hat fuels a plants growth. However, over hundreds an thousands of years, the enzyme finds it difficult to distinguish between oxygen and carbon dioxide, and may attempt to combine oxygen and water, forming a toxic product, which then has to be broken down and recycled which uses even more energy.

It has been stated that, if photorespiration never took place, an additional 200 million people could be fed. Thus, the project RIPE (Realizing Increased Photosynthetic Efficiency), undertaken by the University of Illinois, have been working on solutions on how to achieve this. They noted that photorespiration has a long, complex pathway - so scientists have engineered and rerouted the process which saves energy and resources, boosting plant growth and biomass.
Multiple short pathways were devised and thoroughly tested in 1,700 plants in order to recognise the best, most beneficial pathway. The plants who had been engineered with much shorter pathways for photorespiration were compared with a control group, and had produced 40% more biomass.

Factors affecting photorespiration have to accounted for also, for example: air temperature. The hotter it is, the more photorespiration takes place due to rubisco becoming even more indecisive between oxygen and carbon dioxide.  But we are far from overcoming every single factor, as the team at Illinois say it will most likely take more than a decade for this technology to be translated into plants, especially food crops where it will truly make a difference.

To summarize, by shortening the photorespiration pathway, more energy is conserved, which goes towards the growth of the plant and increased biomasses. Another high-potential solution to the ever -growing food crisis as the global population ages and accumulates.

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Further Reading // Sources:

 https://www.igb.illinois.edu/article/scientists-engineer-shortcut-photosynthetic-glitch-boost-crop-growth-40

https://www.igb.illinois.edu/taxonomy/term/794

https://www.khanacademy.org/science/biology/photosynthesis-in-plants/photorespiration--c3-c4-cam-plants/a/c3-c4-and-cam-plants-agriculture


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