Future long-term manned space missions will raise the question of how food can be supplied to astronauts. Plant biologists from the University of Zurich (UZH) have now studied how agriculture on the moon -or other planets- would be possible.
A nearly weightless environment and soils that contain significantly less nutrients than those on Earth, are not good conditions for lush plant growth. Transporting nutrient-rich soil and fertilizer into space is an ecologically and economically very questionable project, as the UZH announced Wednesday.
Hormone promotes fungal-plant symbiosis
However, the research group headed by Lorenzo Borghi from UZH and Marcel Egli from Lucerne University of Applied Sciences have come up with a possible solution: the plant hormone strigolactone promotes the symbiosis between fungi and fine roots, thus supporting plant growth.
In this symbiosis called 'mycorrhiza', the fungi supply the roots of the plants with additional water, nitrogen, phosphates and trace elements from the soil. Conversely, the fungal threads gain access to sugars and fats produced by the plant. Most plants excrete hormones of the strigolactone family around the root area.
Plants also grow in a weightless environment
Because crops in space have to cope not only with nutrient-poor soils, but also with virtual weightlessness, the researchers have tested how this influences plant growth.
For this purpose, petunias and mycorrhizal fungi were cultured in simulated weightlessness. Petunias are a model organism for nightshade plants such as potatoes, tomatoes and aubergines.
The experiment has shown that a lack of gravity hinders mycorrhization, i.e. the colonization of the roots by the fungi. This reduces the nutrient uptake of the petunias from the soil. However, the plant hormone strigolactone counteracts this effect.
Plants with high levels of hormone release and fungi treated with an artificial strigolactone hormone were found to thrive well in nutrient-poor soils and weightlessness.
Source: Nau.ch