Growing potatoes in high temperatures

Biochemists have found a way to grow potatoes at high temperatures, which could help secure crop yields in the future in view of climate change.

If the temperature is too high, potato plants form significantly lower numbers of tubers or sometimes none at all. Writing in the journal Current Biology, biochemists at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have found this is because a small RNA blocks the formation of tubers, which they have managed to successfully switch off to produce potato plants that are resistant to high temperatures.

The highest potato yields can be gained at moderate temperatures of around 21°C during the day and 18°C at night. At these temperatures and at the correct day length, a protein called SELF-PRUNING 6A (SP6A) is formed, which triggers tuber formation in the plant to prepare it for colder periods. In warmer temperatures, the plants form more green shoots and leaves, and hardly any or no tubers. The few tubers that are formed contain less starch and germinate more quickly, which means they are not as nutritious and rot more quickly.

“Up to now, the mechanism that prevents tuberisation at high temperatures was not known,” explained Prof Dr Uwe Sonnewald, Chair of Biochemistry at FAU.

Led by Sonnewald, the team discovered a small RNA that regulates tuber formation depending on temperature. The RNA is inactive at low temperatures, but if temperatures rise, it blocks the formation of SP6A and thus the formation of tubers.

The researchers then created potato plants in which the effect of the small RNA was deactivated and exposed them to high temperatures in the greenhouse — 29°C during the day and 27°C at night. They found the plants continued to produce good-quality tubers even at the higher temperatures, and plan to test the potato plants under field conditions.

“Our results offer us the means of still being able to grow potatoes in future at increasing temperatures,” said Sonnewald.

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