The protein SMAX1 slows down the production of ethylene, the plant
hormone that triggers or accelerates the ripening of numerous fruits and
vegetables. Ethylene can also trigger other processes in plants. When
less of the gaseous hormone is produced in the plant, this stimulates
the plant to grow long roots and short root hairs. It is also understood
that the SMAX1 brake can be released if the Karrikin signaling pathway
is activated, which brings another hormone into play. This turns on the
production of ethylene, which means that the roots stay short and the
root hairs grow longer.

According to Gutjahr, the mechanism has an enormous influence on the
roots of the legume Lotus japonicus, the model plant for peas, beans,
and lentils which was used in their study. However, the team observed
that the mechanism has a weaker influence on the roots of the model
plant Arabidopsis thaliana. The team is researching how carrikin and
ethylene signaling pathways react to different environmental conditions.
They want to find out how these two signal paths work together with the
sensors with which a plant perceives various environmental influences.

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