Anxiety can be a good thing. It alerts you that something may be wrong, that danger may be close. It helps initiate signals that get you ready to act. But, while an occasional bit of anxiety can save your life, constant anxiety causes great harm. The hormones that yank your body to high alert also damage your brain, your immune system and more if they flood through your body all the time.
Plants don't get anxious in the same way that humans do. But they do suffer from stress, and they deal with it in much the same way. They produce a chemical signal -- superoxide (O2-) -- that puts the rest of the plant on high alert. Superoxide, however, is toxic; too much of it will end up harming the plant.
According to the Vision for Space Exploration, humans will visit and explore Mars in the decades ahead. Inevitably, they'll want to take plants with them. Plants provide food, oxygen, companionship and a patch of green far from home.
On Mars, plants would have to tolerate conditions that usually cause them a great deal of stress -- severe cold, drought, low air pressure, soils that they didn't evolve for. But plant physiologist Wendy Boss and microbiologist Amy Grunden of North Carolina State University believe they can develop plants that can live in these conditions. Their work is supported by the NASA Institute for Advanced Concepts.. Read on at NASA's website.