Flavonols control pollen tube growth and integrity by regulating ROS homeostasis during high-temperature stress

Significance Plant sexual reproduction is required for seed and fruit production and is highly sensitive to elevated temperatures, suggesting that climate change may have profound agricultural impacts through inhibition of this process. During reproduction, pollen tubes must navigate long distances through floral tissues to fertilize ovules. We demonstrate that high-temperature stress increases levels of reactive oxygen species in pollen tubes, which inhibits pollen tube growth. We report that specialized metabolites of the flavonol class prevent reactive oxygen species from reaching inhibitory levels at normal and increased temperatures, thereby promoting pollen viability and pollen tube growth. These results indicate that flavonols enhance reproduction, particularly during heat stress, and could confer protection to plants against the negative effects of climate change.