Biologists from the University of Zurich (UZH) have discovered that the
plant hormone strigolactone could make space farming a possibility. The
research group of Lorenzo Borghi of the University of Zurich and Marcel Egli
of the Lucerne University of Applied Sciences and Arts focused on the
process of mycorrhiza, a symbiotic association between fungi and plant
roots. Through mycorrhiza, the fungal hyphae supply plant roots with
additional water, nitrogen, phosphates, and trace elements from the ground.
In return, they get access to sugar and fat produced by the plant. This
symbiosis is stimulated by hormones of the strigolactone family, which most
plants secrete into the soil around their roots.

In space, cultivated plants have to contend with low-nutrient soil and
microgravity. To look into the effects of these environmental conditions on
plant growth, the researchers cultivated petunias and mycorrhizal fungi
under simulated low gravity conditions. Petunias provide a model organism
for plants of the nightshade family (Solanaceae), which includes tomatoes,
potatoes, and eggplants.

The experiments revealed that microgravity hindered the mycorrhization and
thus reduced the petunias' uptake of nutrients from the soil. But
strigolactone counteracted this negative effect. Plants that secreted high
levels of strigolactone and fungi which the researchers had treated with a
synthetic strigolactone hormone were able to thrive in the low-nutrient soil
despite the microgravity conditions.

[www.media.uzh.ch]