Pruning: The whys and hows

Scientists have shown the main shoot dominates a plant’s growth principally because it was there first, rather than due to its position at the top of the plant.

Collaborating teams from the University of York in the UK and the University of Calgary in Canada discovered why pruning encourages plants to thrive.

Led by professors Ottoline Leyser and Przemyslaw Prusinkiewicz, and published by the journal PNAS, the research showed all shoot tips on a plant can influence each other’s growth.

The research suggests that for a shoot tip to be active, it must be able to export auxin into the main stem. But if substantial amounts of auxin already exist in the main stem, export from an additional shoot tip cannot be established.

The teams went on to show that the recently discovered plant hormone, strigolactone, works at least in part by making it harder to establish new auxin transport pathways from shoot tips, strengthening the competition between auxin sources and reducing branching.