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Rewiring Plants Could Supersize Crops



The newly discovered chemical reactions would allow plants to process carbon dioxide more efficiently. Crops could grow to enormous size.

“We wondered if we could take parts designed by nature, and rewire them together in a mix-and-match approach to get something that’s more efficient for human needs,” said synthetic biologist Ron Milo of the Weizmann Institute, co-author of the study published April 19 in the Proceedings of the National Academy of Sciences.

So-called carbon fixation is essential for the growth of plants, which combine carbon dioxide with water to produce organic compounds in their bodies. But while modern crops have been intensively bred, the essential process of carbon fixation has remained unaltered.

The chemical process used by almost all plants to fix carbon is called the Calvin-Benson cycle. Researchers have tried without success to tweak the cycle’s key enzyme, Rubisco. Evolution appears to have optimized the cycle — but according to Milo’s team, the cycle itself isn’t necessarily optimal.

mogpathways1The researchers designed algorithms that would calculate the combinations of all 5,000 metabolic enzymes identified by science, and return those that required the least energy to fix the most carbon. They found a family of enzyme-driven chemical reactions — malonyl-CoA-oxaloacetate-glyoxylate pathways, or MOG for short — that should be two to three times more efficient than the Calvin-Benson cycle.

For now, MOG pathways exist only in a server farm. The enzymes involved are found in various species of bacteria, not plants. The researchers hope to engineer bacteria with the pathways, and then tissue samples of plants.

Evolution might have stumbled on this solution, but Mother Nature also had to worry about pests, nutrients, water and other factors that modern farmers have under control.

“When you’re working in modern agriculture, what you’re trying to optimize is different from what nature is trying to optimize,” said Milo. “We’re trying to get the most food.”

Images: 1) Kevin Lallier/Flickr. 2) Two MOG pathways/PNAS.

See Also:

Citation: “Design and analysis of synthetic carbon ﬁxation pathways.” By Arren Bar-Even, Elad Noor, Nathan Lewis, and Ron Milo. Proceedings of the National Academy of Sciences, Vol. 107. No. 16, April 20, 2010.
