Circadian Redox Rhythm in Plant-Fungal Pathogen Interactions.

<b><i>Significance:</i></b> Circadian-controlled cellular growth, differentiation, and metabolism are mainly achieved by a classical transcriptional-translational feedback loop (TTFL), as revealed by investigations in animals, plants, and fungi. <b><i>Recent Advances:</i></b> Recently, reactive oxygen species (ROS) have been reported as part of a cellular network synchronizing nontranscriptional oscillators with established TTFL components, adding complexity to regulatory mechanisms of circadian rhythm. Both circadian rhythm and ROS homeostasis have a great impact on plant immunity as well as fungal pathogenicity, therefore interconnections of these two factors are implicit in plant-fungus interactions. <b><i>Critical Issues:</i></b> In this review, we aim to summarize the recent advances in circadian-controlled ROS homeostasis, or ROS-modulated circadian clock, in plant-fungus pathosystems, particularly using the rice (<i>Oryza sativa</i>) blast fungus (<i>Magnaporthe oryzae</i>) pathosystem as an example. Understanding of such bidirectional interaction between the circadian timekeeping machinery and ROS homeostasis/signaling would provide a theoretical basis for developing disease control strategies for important plants/crops. <b><i>Future Directions:</i></b> Questions remain unanswered about the detailed mechanisms underlying circadian regulation of redox homeostasis in <i>M. oryzae</i>, and the consequent fungal differentiation and death in a time-of-day manner. We believe that the rice-<i>M. oryzae</i> pathobiosystem would provide an excellent platform for investigating such issues in circadian-ROS interconnections in a plant-fungus interaction context. <i>Antioxid. Redox Signal</i>. 37, 726-738.