Should we upgrade photosynthesis and grow supercrops? [View all]

[GliderGuider]

Should we upgrade photosynthesis and grow supercrops?

Scientists have long dreamed of upgrading crop plants with the better photosynthetic machinery of free-living cyanobacteria. Until recently all attempts had failed, but now they've taken a huge step forward.

A joint team from Cornell University in New York and Rothamsted Research in the UK has successfully replaced a key enzyme in tobacco plants with a faster version from a cyanobacterium (Nature, vol 513, p 547). Their success promises huge gains in agricultural productivity – but is likely to become controversial as people wake up to the implications.

Upgrading photosynthesis is a different story. If biologists succeed in boosting it by 25 per cent or more, the upgraded plants are going to have a big advantage over their unmodified cousins. And that could spell trouble.

There is a precedent. About 30 million years ago some plants evolved a way to concentrate CO2 like cyanobacteria do. These are called C4 plants, and although they make up only 4 per cent of plant species, they account for 25 per cent of plant biomass. Look out over a grassy savannah and just about every living thing you see will be a C4 plant.

If we fill our fields with supercrops and plant forests of supertrees it seems inevitable that they will turn feral and, like C4 plants before them, come to dominate some ecosystems – though it might take millennia. That prospect will horrify many. When anti-GM campaigners start protesting against the introduction of turbocharged crops, they will have a point: the wisdom of growing superplants in open fields is definitely debatable.

But the arguments in favour – boosting agricultural yield to feed more people with less land while also sucking more CO2 out of the atmosphere – are also powerful. And there's another side to it. Wild animals need to eat too, and we're not leaving much for them. An ecosystem based on superplants would support more life overall.

We just can't leave Mother Nature alone, can we? It's not in our nature, I guess.