Anxiety can be a good thing. It alerts you that something may bewrong, that danger may be close. It helps initiate signals that get youready to act. But, while an occasional bit of anxiety can save yourlife, constant anxiety causes great harm. The hormones that yank yourbody to high alert also damage your brain, your immune system and moreif they flood through your body all the time.
Plants don't get anxious in the same way that humans do. But they dosuffer from stress, and they deal with it in much the same way. Theyproduce a chemical signal -- superoxide (O2-) -- that puts the rest ofthe plant on high alert. Superoxide, however, is toxic; too much of itwill end up harming the plant.
This could be a problem for plants on Mars.
According to the Vision for Space Exploration, humans will visit andexplore Mars in the decades ahead. Inevitably, they'll want to takeplants with them. Plants provide food, oxygen, companionship and apatch of green far from home.
On Mars, plants would have to tolerate conditions that usually causethem a great deal of stress -- severe cold, drought, low air pressure,soils that they didn't evolve for. But plant physiologist Wendy Bossand microbiologist Amy Grunden of North Carolina State Universitybelieve they can develop plants that can live in these conditions.Their work is supported by the NASA Institute for Advanced Concepts.
Stress management is key: Oddly, there are already Earth creaturesthat thrive in Mars-like conditions. They're not plants, though.They're some of Earth's earliest life forms--ancient microbes that liveat the bottom of the ocean, or deep within Arctic ice. Boss and Grundenhope to produce Mars-friendly plants by borrowing genes from theseextreme-loving microbes. And the first genes they're taking are thosethat will strengthen the plants' ability to deal with stress.
Ordinary plants already possess a way to detoxify superoxide, butthe researchers believe that a microbe known as Pyrococcus furiosususes one that may work better. P. furiosus lives in a superheated ventat the bottom of the ocean, but periodically it gets spewed out intocold sea water. So, unlike the detoxification pathways in plants, theones in P. furiosus function over an astonishing 100+ degree Celsiusrange in temperature. That's a swing that could match what plantsexperience in a greenhouse on Mars.
The researchers have already introduced a P. furiosus gene into asmall, fast-growing plant known as arabidopsis. "We have our firstlittle seedlings," says Boss. "We'll grow them up and collect seeds toproduce a second and then a third generation." In about one and a halfto two years, they hope to have plants that each have two copies of thenew genes. At that point they'll be able to study how the genesperform: whether they produce functional enzymes, whether they doindeed help the plant survive, or whether they hurt it in some way,instead.
Eventually, they hope to pluck genes from other extremophilemicrobes -- genes that will enable the plants to withstand drought,cold, low air pressure, and so on.
The goal, of course, is not to develop plants that can merelysurvive Martian conditions. To be truly useful, the plants will need tothrive: to produce crops, to recycle wastes, and so on. "What you wantin a greenhouse on Mars," says Boss, "is something that will grow andbe robust in a marginal environment."
In stressful conditions, notes Grunden, plants often partially shutdown. They stop growing and reproducing, and instead focus theirefforts on staying alive--and nothing more. By inserting microbialgenes into the plants, Boss and Grunden hope to change that.
"By using genes from other sources," explains Grunden, "you'retricking the plant, because it can't regulate those genes the way itwould regulate its own. We're hoping to [short-circuit] the plant'sability to shut down its own metabolism in response to stress."
If Boss and Grunden are successful, their work could make a hugedifference to humans living in marginal environments here on Earth. Inmany third-world countries, says Boss, "extending the crop a week ortwo when the drought comes could give you the final harvest you need tolast through winter. If we could increase drought resistance, or coldtolerance, and extend the growing season, that could make a bigdifference in the lives of a lot of people."
Their project is a long-term one, emphasize the scientists. "It'llbe a year and a half before we actually have [the first gene] in aplant that we can test," points out Grunden. It'll be even longerbefore there's a cold- and drought-loving tomato plant on Mars--or evenin North Dakota. But Grunden and Boss remain convinced they willsucceed.
"There's a treasure trove of extremophiles out there," says Grunden."So if one doesn't work, you can just go on to the next organism thatproduces a slightly different variant of what you want."
"Amy's right," agrees Boss. "It is a treasure trove. And it's just so exciting."
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