Agriculture Genetically Modified Organisms

What’s a C4 Plant Got that a C3 Doesn’t? Better Enzymes for Converting CO2

October 1, 2014

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October 1, 2014 – If we could help plants turn CO2 into sugar at a faster rate we could revolutionize agriculture. That’s what researchers have in mind in trying to make C3 plants act like C4s. Confused?

What are C3 and C4 plants? C4s are the fastest growing. Weeds and corn are both C4s. C3s represent 75% of the world’s food crops and they are notoriously slower growing. We are talking about rice, wheat and potatoes.

So what if we could turn C3s into C4s with a little bit of gene editing? I know. This is genetically modifying the plants to make them convert CO2 into sugars at the same rates as C4s.

Researchers at Cornell University and Rothamsted Research in the UK are doing just that by transplanting genes from cyanobacteria into tobacco (seen in image below). Why tobacco? The plant is very useful in research and I can’t think of a better use rather than smoke it.

The cyanobacteria chosen contains a faster acting rubisco enzyme than is inherent in C3 plants. Unfamiliar with rubisco? It is an acronym that stands for ribulose-bisphosphate-carboxylase-oxygenase. This is the enzyme critical to converting CO2 into sugar in plants.

To successfully achieve the transplant researchers knocked out the native tobacco gene encoded for rubisco. Then they inserted subunit genes from the cyanobacteria.

Short of re-engineering C3 plants to turn them into C4s, the mechanism chosen doesn’t alter the plants anatomically in any way. But it does speed up CO2 conversion which bodes well for future efforts to be applied to C3 staple crops. The end result could mean dramatically higher crop yields for a growing world population.

Results are published in the latest issue of the journal Nature.