News in Science

Discovery to stop plants branching out

A hormone that can literally stop trees branching out has been discovered by an international research team, who say the find could improve productivity of crops around the world.

The research, published in the latest edition of Nature is the result of a collaboration between the University of Queensland (UQ), INRA Versailles and the University of Toulouse.

Co-author Associate Professor Christine Beveridge, at UQ's School of Integrative Biology, says the newly discovered hormone, strigolactone, is a four-ring molecule thought to be derived from carotenoids, the pigments that make carrots orange.

The team has shown strigolactones regulate shoot branching in plants and can be used to control the number of new branches on a plant.

By adding the compound directly to the buds or by supplying it in a solution into the stem of the plant, the number of branches can be altered, she says.

Significant implications

Beveridge says the discovery has significant implications for industries such as forestry and crop farming.

In forestry a lot of time is spent pruning young branches from trees, she says.

"[This is] so they get more energy going into the trunk and less into unwanted branches," Beveridge says.

"In agriculture you might be able to avoid pruning by spraying the crop with this compound or using this compound to discover a more active one that could be applied to that species."

Beveridge says until now scientists have known of fewer than 10 hormones that control a plant's appearance.

"It's probably the case that we're just starting to chip away at these sort of signalling molecules," she says.

"Finding another one is important to [understanding] how to find them and what they do and how they all interact," she says.

Helps in water absorption

Strigolactones also play a role in a plant's ability to absorb water and nutrients, as they promote the beneficial symbiosis with mycorrhizal fungi, which improves nutrient uptake.

"Nearly 80% of plants that you dig up have got this relationship down in their roots with these fungi and that enhances their ability to take up nutrients," she says.

"In Australia that is important because we have really bad soil and the plants have to work hard to get water or nutrients out of the soil.

"This discovery is providing the biosynthetic genes for the compound that's needed to enhance the nutrient water uptake."

The research could also help with the management of parasitic weeds that devastate staple food crops in parts of Africa and Asia.

Having discovered genes involved in the biosynthesis of strigolactones, scientists can now start modifying crops to make them resistant to parasitic weeds, Beveridge says