One key to the long-term exploration of Mars will be figuring out how to get plants to grow there in greenhouses - they're natural factories for air and food. Since they evolved on Earth, they have no mechanism for surviving in low pressures, which would be a requirement for off-planet greenhouses; they think they're drying out even when there's plenty of water. One solution might be to biochemically adjust levels of hormones that initiate the drought instinct.