Several years ago NASA included lettuce grown in space on the menu of astronauts residing aboard the International Space Station (ISS). In addition to flour tortillas and coffee powder, astronauts can eat a salad grown in special chambers on the International Space Station where the temperature and the amount of water and light that plants need to grow and mature are controlled.
But new research published in Scientific Reports and npj Microgravity reveals that lettuce grown in weightless environments is more vulnerable to infection by human pathogens than those grown on Earth, so it can become a transmitter of diseases among humans. residents of the ISS and derail their mission.
Specifically, researchers at the University of Delaware (United States) grew lettuce in conditions that mimicked the environment aboard the ISS and observed that plants exposed to this simulated microgravity were more prone to infections by a human pathogen such as salmonella. Noah Totsline, who participated in the research during his graduate studies, explained how the fact of weightlessness and not knowing which direction it is, whether up or down, confuses the plant's response to a stressor like a bacteria.
Thus, while in plants grown on the Earth's surface the stomata - the small pores in the leaves and stems that the plant uses to breathe - quickly close to defend the plant when they detect a bacteria nearby, the researchers discovered that in lettuce grown under microgravity they opened widely, making it easier for salmonella to invade the leaf tissue.
The researchers then tried adding a helper bacteria that is shown to promote plant growth and their ability to cope with pathogens or other stressors such as drought to see if it helped lettuces grown in microgravity defend themselves against salmonella. And they discovered that no, this auxiliary bacteria was also not capable of triggering the biochemical response that would force the plant to close its stomata.
The authors of the experiment do not know the reason for this failure, but they suspect that the simulated microgravity overwhelms the plant and prevents it from communicating with the auxiliary bacteria that would help it defend itself, making it easier for salmonella to invade the plant.
This research opens the debate on the food security of agricultural products that, in the future, can be grown in space, both with an eye on future space missions to Mars or the Moon and in projects that advocate seeking cultivation spaces alternatives to the constant loss of cropland on the earth's surface and the increase in population.
