BioEd Online

A gene that helps plants decide when and where to sprout new branches has been discovered. The find may give rise to less wasteful crops and more beautiful bushes.

"Branching has a profound effect on the architecture of a plant," says Ottoline Leyser of the University of York, UK, who is one of the researchers behind the study. The simple yes/no decision of whether to sprout a side shoot essentially dictates the plant's ultimate shape.

Leyser and her colleagues identified the gene, called MAX3, in Arabidopsis thaliana, a weed commonly studied by geneticists. Plants that sport unusually high numbers of side shoots tend to have mutations in this gene, the researchers report in Current Biology¹.

This shows that the protein produced by MAX3 probably functions to inhibit branching as the main stem grows. Although the mechanism by which it does this is unclear, Leyser suspects that the protein binds to molecules called carotenoids. She thinks the protein chops the molecules into fragments that send signals to the growing cells and tell them how to divide. If this is the case, says Leyser, the team will have discovered a new plant hormone.

Branching out

Knowing exactly how plants organize their branching would be valuable, Leyser explains. Plant biologists already know that other hormones called auxin and cytokine influence branching, but these have a huge range of other developmental effects. "If you want to change the plant without altering 50 million other things it would be best to go for the MAX pathway," she quips.

Disrupting MAX3 could create more beautiful ornamental plants, suggests Harry Klee of the University of Florida, another member of the research team. "One could alter flowering plants or bushes to produce more branches, giving them a fuller appearance," he says.

And in the case of crops, less could well mean more, Klee adds. Trees with fewer branches would yield better-quality timber, and wheat plants might produce more nourishing ears if they spent less of their resources on sprouting sideways.