Researchers are collecting Arabidopsis thaliana in lunar soil. Image courtesy of Tyler Jones
Plants in experiments are placed in tubes ready for genetic analysis. Photo by Tyler Jones
The relevant research results were published in “Communications-Biology” on May 12.
Robert Ferl and colleagues at the University of Florida tested whether lunar soil could support plant life by growing Arabidopsis thaliana, a flowering plant native to Europe and Africa, in twelve soil samples prepared by Apollo 11 , 12 and 17 lunar mission collections.
Anna-Lisa Paul (left) and Rob Ferl (right) working on lunar soil in the lab Photo by Tyler Jones
Rob Ferl is weighing lunar soil, which has been sealed in test tubes since it was brought back from the Apollo 11, 12 and 17 missions. Image via Tyler Jones
Because the samples collected on each mission came from different soil layers, the Apollo 11 samples were exposed to the lunar surface longer than the Apollo 12 and 17 samples. The researchers examined whether there were differences in growth and gene expression between the plants and compared to Arabidopsis thaliana grown in 16 samples of Earth’s volcanic ash, which is similar in particle size and mineral composition to lunar soil.
The researchers found that although seeds could grow in all soil environments, plants in lunar soil grew more slowly than in volcanic ash, took longer to develop leaves, and had more stagnant roots. While some lunar plants were similar in shape and color to those grown in volcanic ash, others were stunted and contained reddish melanin—a classic sign of plant stress. Genetic analysis of three smaller, darker plants showed that they had more than 1,000 genes (mostly related to stress) that were expressed at different levels than those in the ash.
By day 16, plants in the volcanic ash (left) and those in the lunar soil (right) had obvious physiological differences. Image via Tyler Jones
In addition, the researchers found that plants grown in the Apollo 11 samples were weaker than those in the Apollo 12 and 17 samples, and expressed more and different levels of genes than those in the volcanic ash. Plants from the Apollo 11, 12 and 17 collections expressed 465, 265 and 113 different levels of the gene, respectively. 71% of these genes were associated with stress caused by salts, metals and molecules containing reactive oxygen species.
Anna-Lisa Paul is doing delicate plant harvesting for subsequent genetic analysis. Image via Tyler Jones
These findings suggest that lunar soil, while useful for cultivation, does not support plant growth at the same level as volcanic ash—especially the lunar soil that is more exposed to the lunar surface. The researchers speculate that cosmic rays and the solar wind damage the lunar soil, and that the lunar soil contains tiny iron particles that may induce a stress response in plants, impairing their development.
