The lab experiment Carreiras and his colleagues carried out involved growing the grapevines under controlled conditions for a few months and then dividing them into groups. The team applied a solution containing mixtures of bacteria collected from the salt marshes to some of the groups in the weeks leading up to the heatwave. Then they whacked up the heat.
Afterwards, the team analysed the leaves, for example shining strong lights through them to show up the structure of cells. This revealed that the vines treated with the second bacterial collection were barely affected by the heat. Usually, one would expect to see damage to the plant’s cell walls after such an assault, says Carreiras, but for those grapevines very little such damage was visible.
“Microbes have been adapting and evolving for thousands of years,” says Katherine Duncan, a microbial chemist at the University of Strathclyde who searches for new drugs that are produced by marine bacteria. “It makes sense to look to them for natural solutions.”
However, the application of microbes to crops is still in its infancy, Duncan cautions. She says it will be important to work out how much farmers might have to tailor microbial species to particular plants.
“I think it’s interesting that they went to marine sources,” says António Graça of Sogrape, a wine company in Portugal. Graça has a working relationship with one of the authors of the paper, though was not involved in the study. Separately, Sogrape is exploring the application of marine algae extracts to grapevines, to see if that helps the plants cope with drought.