Brief Exposure to Bright Light can Boost Antioxidant Production in Space Plants

Few pulses of bright light a day could help increase antioxidant production in space plants, a new study has found. Researchers say that the nutrient-rich plants could protect astronauts from eye damage during long space flights.

The study, conducted by University of Colorado Boulder researchers, shows that green leafy vegetables exposed to short bursts of light produce a nutrient called zeaxanthin.

Zeaxanthin  is known to prevent chronic eye disease such as age-related macular degeneration (AMD) and cataracts.

Plants produce zeaxanthin when exposed to bright light. The production usually happens when the plants are under physiological stress such as dealing with a water shortage. As plants can't use all the available light; they produce zeaxanthin- a compound that helps remove excess light, researchers said.

"Our eyes are like a leaf-they are both about collecting light," said Barbara Demmig-Adams, professor of distinction in the Department of Ecology and Evolutionary Biology and a co-author of the study. "We need the same protection to keep us safe from intense light."

Space Gardening                                                                 

Current research on space farming is mostly focused on providing quality nutrients to seedlings to increase biomass. However, researchers in the present study have shown that exposing plants to physiological stress might help increase antioxidant levels in plants.

"There is a trade-off," said Demmig-Adams, according to a news release. "When we pamper plants in the field, they produce a lot of biomass but they aren't very nutritious. If they have to fend for themselves-if they have to defend themselves against pathogens or if there's a little bit of physical stress in the environment-plants make defense compounds that help them survive. And those are the antioxidants that we need."

For the study, researchers used Arabidopsis plants and demonstrated that few pulses of bright light per day could coax the plants to produce more zeaxanthin. The pulses were brief and didn't affect any other biochemical process in the plant.

"When they get poked a little bit with light that's really not a problem, they get the biomechanical machine ready, and I imagine them saying, 'Tomorrow there may be a huge blast and we don't want to be unprepared,' " Demmig-Adams said in a news release.

Astronauts could use dietary supplements with Zeaxanthin. However, research has shown that human bodies absorb the antioxidant from plants better than from pills. Also, growing and tending to plants during long spaceflight could boost astronauts' morale.

Arabidopsis plants aren't edible. Researchers are hopeful that other plants could produce antioxidants via a similar mechanism.

The study was funded by the National Science Foundation and CU-Boulder's Undergraduate Research Opportunities Program and is published in the journal Acta Astronautica.