Abstract

Blue light (BL) receptor phototropins (phots) regulate numerous BL-induced physiological responses through NPH3/RPT2-like (NRL) family members. However, how phots and NRL proteins regulate plant immunity remain incompletely understood. This study demonstrates that Stphot2 negatively regulated resistance against Phytophthora infestans, the causal agent of late blight, in potato and Nicotiana benthamiana. Stphot2 interacts with an NRL protein, StNRL-30, which functions as a susceptibility factor. Homodimerization and C-terminal consensus sequence (RxSΦS) of StNRL-30 are essential for accelerating P. infestans infection. The study identifies StNRL-30’s interaction with mitochondrial Peroxiredoxin-IIF (StPRXIIF), which positively regulates resistance against P. infestans. StPRXIIF overexpression upregulates mitochondrial alternative oxidase genes and salicylic acid pathway genes, while downregulating jasmonic acid pathway genes. StNRL-30 initiates StPRXIIF degradation, enhanced by Stphot2. In addition, BL treatment promotes StPRXIIF turnover and induces the translocation of the StNRL-30–StPRXIIF complex from the plasma membrane to the chloroplasts. These findings demonstrate how the BL receptor Stphot2, along with StNRL-30, modulates plant immunity by affecting the stability and localization of the positive immunoregulator StPRXIIF, providing insights into BL and plant immunity crosstalk.