Hormone Makes Plant Growth Possible in Space

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.

For more, read the press release from UZH.