COP9 signalosome complex subunit-7-mediated regulation of cAMP levels contributes to autophagic degradation and pathogenesis of rice blast fungus Magnaporthe oryzae

Abstract

O_LIPhoto-dependent processes, including circadian rhythm, autophagy, ubiquitination, neddylation/deneddylation, and metabolite biosynthesis, profoundly influence microbial pathogenesis. Although a photomorphogenesis signalosome (COP9/CSN) has been identified, the mechanism by which this large complex contributes to pathophysiological processes in filamentous fungi remains unclear. C_LIO_LIHere, we identified eight CSN complex subunits in the rice blast fungus Magnaporthe oryzae and functionally characterized the translocon subunits containing a nuclear export or localization signal (NES/NLS). C_LIO_LITargeted gene replacement of these CSN subunits, including MoCSN3, MoCSN5, MoCSN6, MoCSN7, and MoCSN12, attenuated vegetative growth and conidiation in M. oryzae and rendered non-pathogenic deletion strains. MoCSN7 deletion significantly suppressed arachidonic acid catabolism, compromised cell wall integrity, subverted photo-dependent ubiquitination, and abolished photo-responsiveness. Surprisingly, we also discovered that MoCSN subunits, particularly MoCsn7, are required for the cAMP-dependent regulation of autophagic flux. C_LIO_LITherefore, MoCSN significantly contributes to morphological, physiological, and pathogenic differentiation in M. oryzae by fostering cross-talk between multiple pathways. C_LI