Increased protein solubility contributes to heat priming of the plant pathogenic fungus Botrytis cinerea

Botrytis cinerea causes grey mold disease in leading crop plants. The disease develops only at cool temperatures, but the fungus remains viable in warm climates and can survive periods of extreme heat. We discovered a strong heat priming effect in which the exposure of B. cinerea to moderately high temperatures greatly improves its ability to cope with subsequent, potentially lethal temperature conditions. We showed that priming promotes protein solubility during heat stress and discovered a group of priming-induced serine-type peptidases. Several lines of evidence, including transcriptomics, proteomics, pharmacology and mutagenesis data, link these peptidases to the B. cinerea priming response, highlighting their important roles in regulating priming-mediated heat adaptation. By imposing a series of sub-lethal temperature pulses that subverted the priming effect, we managed to eliminate the fungus and prevent disease development, demonstrating the potential for developing temperature-based plant protection methods by targeting the fungal heat priming response. Overall design: Here we show that MHT had a strong priming effect on B. cinerea, namely it greatly improved the ability of the fungus to cope with a subsequent potentially lethal heat stress. we were able to differentiate the priming from a general heat stress effect and showed that priming improves protein solubility during severe heat stress.