The conserved CERES-XIAN axis mediates double-stranded RNA-triggered plant immunity through modulating mitochondrial...

Pattern-triggered immunity (PTI) is the first layer of the plant immune system, which relies on the perception of pathogen-associated molecular patterns. Recently, it has been found that double-stranded RNA (dsRNA), a hallmark of viral invasion, triggers typical PTI responses; however, the underlying signaling pathways are not yet elucidated. Here, we identify a plant-specific, leucine-rich repeat family protein, AtCERES, involved in dsRNA-triggered activation of defense-related genes, MPK3/6 phosphorylation and seedling growth inhibition. AtCERES directly binds the mitochondrial glycoprotein AtXIAN, which also positively regulates dsRNA-triggered immune responses. Upon dsRNA perception, AtXIAN and AtCERES affect the level of mitochondrial reactive oxygen species (mROS), which is independent of respiratory burst oxygenase homologs D. Importantly, the generation of mROS is required for immune responses triggered by dsRNA. Together, our results uncover the function of AtCERES and AtXIAN as components of the dsRNA-triggered immune pathway, and suggest a link between mROS and antiviral immunity in plants.