Spermidine enhances the heat tolerance of <i>Ganoderma lucidum</i> by promoting mitochondrial respiration driven by fatty acid β-oxidation

Polyamines are stress-responsive molecules that enhance the tolerance of plants to multiple abiotic stresses by regulating a variety of biological processes. Our previous research indicated that heat stress induces the the biosynthesis of polyamines and promotes the conversion of putrescine to spermidine in <i>G. lucidum</i>, but the physiological role of elevated spermidine levels is yet to be elucidated. In this study, our findings demonstrated that spermidine enhances the heat tolerance in <i>G. lucidum</i> and that mitochondrial respiration is essential for spermidine-enhanced heat tolerance. This study elucidated a preliminary mechanism by which spermidine enhances heat tolerance of <i>G. lucidum</i> and provided a new insight into the understanding of how microorganisms resist heat stress.