For the first time in history, scientists from the University of Florida (USA) they have managed to grow plants in the laboratory on lunar soil brought back by the Apollo missions, a milestone that opens the doors to important advances in agricultural experimentation outside our planet.
In a paper published in the journal Communications Biology, the researchers showed that plants can successfully sprout and grow on lunar soil. The study details how plants respond biologically to soil on the Moon, also known as lunar regolith, which is radically different from soil found on Earth.
This work is a first step towards one day growing plants for food and oxygen on the Moon. or during space missions. More immediately, this research comes as the Artemis program plans to return humans to the Moon.
“Artemis will require a better understanding of how to grow plants in space,” said Rob Ferl, one of the study’s authors and distinguished professor of horticultural sciences at the UF Institute of Food and Agricultural Sciences (UF/IFAS).
Even in the early days of lunar exploration, plants played an important role, recalls Anna-Lisa Paul, also one of the study’s authors and a research professor of horticultural sciences at UF/IFAS.
Already then plants were used to show “that the soil samples brought back from the Moon did not harbor pathogens or other unknown components that could harm terrestrial life, but those plants were only ‘dusted’ with lunar regolith and were never actually grown on it” Paul explains.
Paul and Ferl are internationally recognized experts in the study of plants in space. Through UF’s Space Plant Laboratory, they have sent experiments on space shuttles, to the International Space Station, and on suborbital flights.
“For future longer space missions, we could use the Moon as a hub or launch pad. It makes sense that we would want to use the soil that is already there to grow plants.” Ferl stresses. So what happens when plants are grown on lunar soil, something that is totally outside of a plant’s evolutionary experience? What would plants do in a lunar greenhouse? Could we have lunar farmers?
To begin to answer these questions, Ferl and Paul designed a seemingly simple experiment: plant seeds in lunar soil, add water, nutrients, and light, and record the results.
They only had twelve grams of lunar soil
It was not an easy task, because the scientists only had 12 grams -barely a few teaspoons- of lunar soil to carry out the experiment. On loan from NASA, this soil was collected during the Apollo 11, 12 and 17 missions to the Moon. Paul and Ferl applied three times over the course of 11 years for the opportunity to work with lunar regolith.
The small amount of soil, not to mention its incalculable historical and scientific importance, meant that Paul and Ferl had to design a carefully designed, small-scale experiment. To cultivate his tiny lunar garden, they used thimble-sized holes in plastic dishes normally used to grow cells.
Each well functioned as a flowerpot. Once they filled each “pot” with about a gram of lunar soilthe scientists moistened the soil with a nutrient solution and added a few seeds of the Arabidopsis plant.
Arabidopsis, the chosen plant
Arabidopsis is widely used in plant science because its genetic code has been fully mapped. Growing Arabidopsis in lunar soil allowed the researchers to better understand how the soil affected plants, down to the level of gene expression.
As points of comparison, the researchers also planted Arabidopsis in JSC-1A, a terrestrial substance that mimics real lunar soil, as well as in simulated Martian soils and terrestrial soils from extreme environments. Plants grown on these non-lunar soils were the control group for the experiment.
Before the experiment, the researchers they were not sure if the seeds planted in the lunar soils would sprout. But almost all of them did.
“We were surprised. We hadn’t anticipated it,” says Paul. “That told us that lunar soils didn’t disrupt the hormones and signals involved in plant germination.”
However, over time, the researchers observed differences between the plants grown in lunar soil and the control group. For example, some of the plants grown on lunar soils were smaller, grew more slowly, or were more varied in size than their counterparts.
These were all physical signs that plants were working to deal with the chemical and structural makeup of the lunar soil, explains Paul. This was further confirmed when the researchers analyzed the gene expression patterns of the plants.
“At the genetic level, plants evolved the tools typically used to deal with stress factors., such as salt and metals or oxidative stress, so we can deduce that plants perceive the lunar soil environment as stressful, explains Paul. Ultimately, we’d like to use gene expression data to help address how we can enhance stress responses to the level where plants – particularly crops – are able to grow on lunar soil with very little impact to their environment. Health”.
How plants respond to lunar soil may be related to where the soil was collected, say Ferl and Paul, who collaborated on the study with Stephen Elardo, an associate professor of geology at UF.
For example, the researchers found that the plants with the most signs of stress were those grown in what lunar geologists call mature lunar soil. These mature soils are the ones that are exposed to the most cosmic wind, which alters their composition. On the other hand, plants grown on comparatively less mature soils fared better.
Growing plants on lunar soils can also change the soils themselves, Elardo says. “The Moon is a very, very dry place. How will the minerals in the lunar soil respond to growing a plant on it, with the added water and nutrients? Will the addition of water make the mineralogy more hospitable to plants?” ?” he wonders.
Follow-up studies will be based on these and other questions. For now, scientists celebrate having taken the first steps toward growing plants on the Moon.
“We wanted to do this experiment because, for years, we’ve been asking ourselves this question: Would plants grow on lunar soil?” Ferl explains. “The answer, it turns out, is yes.”
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