Building Tough Crops to Grow on Mars

Sept. 1, 2006 — Imagine tomatoes that grow through the chill of winter or a front lawn that doesn't need watering all year.

Genes from microorganisms that survive the freezing Arctic or scalding deep-sea vents are being used to engineer such tough plants so they might suitable for the hostile environment of outer space.

The plants, which someday could be grown in greenhouses on Mars or on a spacecraft, could be used to help purify air and water as well as feed astronauts.

They could also be sowed on Earth as hardy crops or for use in low-maintenance gardens.

"Just think if you didn't have to water your grass for an extra week. That would be a real plus," said Wendy Boss, a professor of plant biology at North Carolina State University.

Boss and Amy Grunden, associate professor of microbiology, and their team have already proven that their approach works at the cellular level.

More recently, they achieved promising results with seeds and seedlings of mustard weed able to withstand hot temperatures.

To make their extreme plants, Boss and Grunden borrowed a gene from a microbe known as Pyrococcus furiosus, which thrives in the boiling waters of shallow and deep-sea hydrothermal vents.

Inserting a gene from a microorganism into a plant is not new.

However, scientists who do it usually change the DNA sequence so that it can be properly read by the plant's cells.

Boss and Grunden skipped that part. Instead they took a chance that the particular gene they chose would work inside the plant.

They were right.

The gene is called superoxide reductase. It creates an enzyme that combats toxic free radicals produced when the microbe encounters stressful conditions.

Plants have enzymes that combat free radicals, but the enzymes are not as efficient or effective as those from the microbe. When conditions get too hot or too cold or too acidic, the free radicals kill the plant.

But when the plant has the microbe's gene, it's able to survive more extreme conditions.

These kinds of plants would be easier and cheaper to grow in space-based greenhouses than regular plants, which would require costly temperature- and pressure-controlled environments.

But it could be decades before we see vegetable stands on Mars.

"It's one thing to incorporate a gene here and a gene there…but the metabolism of a cell is a very complex thing," said Howard Levine, a project scientist at Kennedy Space Center in Florida, who has flown many biological experiments on space shuttles.

"One challenge will be whether these genes can be incorporated successfully into the whole picture of the metabolism."