Scientists at the John Innes Centre have revealed the first detailed view of how strigolactones – hormones in plants – slow down root growth. These hormones play a crucial role in how plants respond to light and are required for symbiotic associations with beneficial soil fungi, such as mycorrhizal fungi, which help plants to access nutrients from the soil.

The new study, published in Nature Communications, could lead to new crop varieties that are better at taking up nutrients from the soil, benefiting global food security.

The scientists, led by Dr Jonathan Hejatko, studied strigolactones by soaking rice seeds in the hormone, which slowed the growth of their primary roots – the first roots to emerge from the seed – and triggered the growth of lateral roots. To understand why this happened, the team crystallised the DWARF14 enzyme and then determined its structure using a technique called X-ray crystallography.

The research team found that DWARF14 works together with another enzyme called MAX2 to convert a molecule called carlactone into strigolactone. Strigolactone acts on the primary root meristem – a region where cells constantly divide – to inhibit the production of new cells and thus slow root growth.

The work also reveals how the abundance of strigolactone in plants changes in response to different environmental conditions, such as light and nutrient availability. This is particularly important for plants because their root systems need to be adaptable in changing environments.

The findings are a significant step forward in understanding the molecular basis of strigolactone action, which could lead to the development of crop varieties with enhanced traits such as improved nutrient uptake efficiency and drought resistance.

“We now have a detailed understanding of how strigolactones work,” said Dr Hejatko. “This knowledge could be used to develop new crop varieties that are more resistant to drought and have improved nutrient uptake efficiency, which would benefit global food security.”