By making potatoes heat-resistant we can ensure bountiful harvests

Rises in temperatures can harm crop yields by reducing plants’ ability to cope. This applies to potatoes, which are a dietary staple across much of the world. In a warming world potatoes may fall on hard times and so might entire communities that depend on them.

In higher temperatures, potato plants tend to form much fewer number tubers. Yet a team of biochemists at Friedrich-Alexander-Universität Erlangen-Nurnberg has discovered why that is and what to do about it.

Potato plants produce the highest yields at moderate temperatures, or around 21 degrees Celsius by day and 18 degrees Celsius at night. “At these temperatures and at the correct day length, a protein that induces the formation of tubers called SELF-PRUNING 6A (SP6A) is formed,” explain the scientists, who published their findings in the journal Current Biology. “This triggers tuber formation in the plant to prepare it for colder periods.”

Warmer temperatures, however, cause plants to switch to growing more green shoots and leaves but hardly any or no tubers. The scientists tested this by keeping the plants in a greenhouse where temperatures were set higher: 29 degrees by day and 27 degrees at night. They found that even the few tubers that were formed contained less starch and germinated faster so they were less as nutritious and rotted more quickly.

“Up to now, the mechanism that prevents tuberisation at high temperatures was not known,” explains Prof. Uwe Sonnewald, chair of biochemistry at the university who led the research team. His team discovered that a small ribonucleic acid (RNA), made of 19 nucleotides, regulates tuber formation in the plant and it responds to temperature changes. It is inactive at low temperatures, but it springs into action at higher ones.

By deactivating this small RNA in genetically engineered potato plants, the researchers managed to ensure that even in higher temperatures the plants continued producing high-quality tubers. “Our results offer us the means of still being able to grow potatoes in future at increasing temperatures,” Sonnewald says. By tinkering with this RNA, we’ll be able to ensure that potato yields will remain high even in an ever-warming world.