Thermal priming enhances heat tolerance and yield in tomatoes after recurrent heat stress

A new study led by Dr. Justyna Olas from the Leibniz Institute for Horticultural Sciences has found that moderate heat exposure can enhance tomato plants' resilience to subsequent severe heat stress, a phenomenon known as thermal priming. Published in The Plant Journal, the research reveals that tomatoes can develop a form of memory in response to initial heat stress, allowing them to better withstand subsequent heat events.

This "thermal priming" reprograms the plants, enabling them to quickly and effectively respond to future heat stress. In controlled experiments, plants primed with moderate heat stress showed a 41% increase in fruit production and total fruit mass compared to unprimed control plants after being subjected to recurrent severe heat stress.

In a field trial conducted in 2025, primed plants produced approximately 53% more fruit than non-primed plants under fluctuating environmental conditions. The protective effect of thermal priming lasted for up to 10 days, after which it diminished. The study also identified the transcription factor SlHSFA2 as a key player in this process, regulating the activation of SlBAG6, a gene involved in the thermal memory response.

While the mechanism linking this molecular response to increased yield is still unclear, the findings suggest that thermal priming could be a valuable strategy for improving tomato yields under heat-stressed conditions.