Circadian Regulation\nof the Rice Immune Response during\nRice Blast Infection via Metabolic and Calcium Signaling

The circadian clock is crucial in plant immunity and\nmetabolism,\nyet the coordinating mechanisms remain elusive. In the present study,\ntranscriptome analysis of M. oryzae-infected rice leaves and rhythmic analysis showed reduced amplitudes\nof circadian and phytochrome genes, impacting immune response, metabolic\npathways, and calcium signaling. The amplitudes of pattern-triggered\nimmunity (PTI)-related genes declined, while the rhythmicity of effector-triggered\nimmunity (ETI)-related genes disappeared. Moreover, alterations in\nthe phases of metabolic pathways were observed, potentially involved\nin immune response regulation like phytohormone biosynthesis. Calcium\nsignaling exhibited a circadian pattern similar to that of the whole-transcriptome\nanalysis. The administration of CaCl<sub>2</sub> alleviated, whereas\nthe calcium ion chelator EGTA aggravated, the phenotypes of rice blasts,\nsuggesting their role in regulating the circadian clock-mediated immune\nresponse in rice. Our study highlighted the significance of circadian\nregulation in rice blast-induced immune modulation, which may contribute\nto developing immunomodulators and the formulation of chronobiology-based\nprecise therapeutic regimens.