Outer space offers plant breeders some curious advantages

PLANTS GROWNX in orbit, and thereby deprived of the comforting directional pull of Earth’s gravity, typically struggle to distinguish up from down. This makes it harder for them to carry water and nutrients around themselves. It also fouls up their ability to draw carbon dioxide needed for photosynthesis from the air. The stress caused by all this seems to increase the level of genetic mutation induced by a given amount of radiation—of which there is much in space, in the form of cosmic rays and effluvia from the sun. And mutations are the lifeblood of plant breeders.On Earth, breeders induce them by exposing plants and seeds to radioactive isotopes, -rays and so on. Most are harmful. But some hit the jackpot, conferring properties like drought resistance, blight resistance or shorter stems, favoured by farmers, and sweeter flavours, brighter colours or thinner peel, favoured by consumers. Plucked from their progenitors by selective breeding and added to cultivars, such mutations are worth millions. Mutagenesis, then, is an important business.