A team of scientists has shown for the first time that plants can grow on Moon regolith, collected during the Apollo 11, 12 and 17 missions. There is renewed interest in the lunar environment since NASA announced its Artemis programme, which will return humans to the moon.
Seeds from the mouse-ear cress (Arabidopsis thaliana) sprouted on lunar regolith between 48 and 68 hours after planting and developed what looked like normal stems (Commun. Biology, doi:10.1038/s42003-022-03334-8). The roots were somewhat stunted compared with a terrestrial mimic of real lunar soils. Mineral fertiliser was added to help the plants grow.
Scientists at the University of Florida also looked at changes in the expression of genes. All plants grown on Moon dust showed significant changes in genes linked to stresses from salt, metals and reactive oxygen species, compared with those grown on a lunar soil mimic, JSC-1A. This ‘suggests the plants are experiencing nutrient stress that is showing up as changes in the levels of genes related to things like phosphate starvation,’ comments Simon Gilroy, a plant scientist at the University of Wisconsin-Madison.
‘These plants also are triggering responses to oxidative stress and switching on their defences. This all points to the plants not being happy but coping by triggering the systems that allow them to adapt to these kinds of stresses,’ he adds.
The regolith particles are sharp and tend to clump together when water is added, creating a texture resembling concrete, notes Gilroy. ‘The chemistry of the particles is very different from the Earth,’ he adds. ‘Plants evolved to exploit the chemistry of the Earth and so how the roots would interact with the regolith was a big unknown.’
The Florida scientists had applied three times over a period of 11 years to NASA to ask to work with lunar regolith. The rarity of lunar material meant that each pot was filled with about a gram of lunar soil. The researchers say that they were surprised at just how normally the seeds germinated, which indicated that the conditions did not interfere with hormones and signals involved in plant germination.
The findings suggest it will be necessary to add nutrients to lunar regolith to keep plants happy. ‘It now looks like growing in regolith is a realistic strategy to sustaining astronauts on the Moon for the long haul, with plants contributing to their life support systems,’ explains Gilroy. ‘This is incredibly exciting for space plant biologists as it takes us big step towards the goal of a 'greenhouse' on the lunar surface.’