These Fungi Could Turn Martian Dust Into Farmland: Milky Way News

EARTH, Laniakea Supercluster—Green leaves could someday poke up through red Martian soil, thanks to the detoxification powers of fungi.

Scientists from the Federal University of the State of Rio de Janeiro, Winston-Salem State University, and Florida Institute of Technology published a review on the subject titled "Selection of beneficial fungi for plants with the potential to metabolize lunar and Martian regolith" in April. It was led by Jéssica Carneiro Oliveira and published in Frontiers in Astronomy and Space Sciences.

The paper discussed how fungi can help plants grow through abiotic stress—damage caused by the nonliving parts of an environment, like drought, flooding, and toxic metals, rather than by pests or disease. Minimizing abiotic stress can help plants thrive.

"Nature has found ways of solving a lot of the challenges that we face when we think about agriculture off world," Andrew Palmer, one of the review's co-authors, told Milky Way News. "And so I think leveraging those solutions by selecting the right bacteria and the right fungi to fix those problems is pretty natural."

Palmer, an associate professor at Florida Institute of Technology, described how the exchange between the fungi and plants is beneficial for both parties.

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"The fungi release compounds that can help trap up the iron and pull it in the solution so that it dissolves properly, and then that gets into the plants. And so, they share it," he said. "The plants give them certain nutrients, and in return, the fungi give them things like iron or phosphate that they may not be able to uptake as easily."

The fungi he referred to are called arbuscular mycorrhizal fungi, or AMF. They live inside plant roots and spread microscopic threads through the soil, running something like an underground barter economy: the fungi scavenge minerals the roots can’t reach, and the plant pays them in sugar.

Regolith, the loose dust and broken rock that blankets Mars and the moon, is too toxic for plants to thrive in right now. It carries enough iron to stress plants and is alkaline enough to keep other nutrients out of reach. According to the review, fungi can improve the plants’ iron uptake and help them withstand heavy-metal toxicity. The authors also see a role for fungal bioremediation (using living things to neutralize toxic substances) to help plants thrive on strange new worlds.

Fungi from the Penicillium genus are great candidates for bioremediating regolith with perchlorate, which make up 0.4 to 0.6 percent of the soil at NASA’s Phoenix landing site. While perchlorate is sometimes naturally occurring, it can harm human health; food with high perchlorate levels can make it harder to absorb iodine. Hopefully, that means these fungi could help astronauts in more ways than one.

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Palmer, though, said the process on lunar and Martian surfaces would be more like "mediation" than "remediation."

"Remediating implies that, at one time, it was good…The Mars surface has to be corrected and adjusted so that plants will grow there," he said.

Palmer said that the setup could look a bit like Andy Weir’s The Martian, with supplies landed on Mars' surface before any humans arrive to start farming.

The research team hopes the review will lead to more applied research. The paper stated that there has been little testing of fungi in actual regolith samples. Doing so with the real thing would be difficult or impossible since lunar regolith samples are so limited, and there are no Martian samples to work with. To get around this, researchers rely on simulants—Earth-made stand-ins for lunar and Martian regolith. When those studies can happen, it will also be important to test under space-like conditions, like with radiation exposure, which has never occurred.

People often wonder when Palmer speaks at events why this research is important. After all, space-related research can take a lot of resources. But he explained that it may not be as disconnected from Earth as some think.

A study published in Catena found that U.S. cropland is losing topsoil about five times faster than new soil forms, and it may only get worse, especially if greenhouse gas emissions keep rising.

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In the meantime, researchers are trying to find solutions that will strengthen agriculture. Palmer mentioned that fungi on the International Space Station are evolving separately from fungi on Earth, and they could be solutions for terrestrial and space agriculture alike.

"Thinking about the future and thinking about space actually teaches us, I think, quite a lot about life on our planet and how life on our planet got started and how it persists," he said.

And if there's one thing the universe is great at doing, it's helping people realize that, like mycorrhizal networks, everything is connected.