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

Abstract

SummaryPhoto-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.Here, we identified eight CSN complex subunits in the rice blast fungusMagnaporthe oryzaeand functionally characterized the translocon subunits containing a nuclear export or localization signal (NES/NLS).Targeted gene replacement of these CSN subunits, includingMoCSN3,MoCSN5,MoCSN6,MoCSN7, andMoCSN12, attenuated vegetative growth and conidiation inM. oryzaeand rendered non-pathogenic deletion strains.MoCSN7deletion 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.Therefore, MoCSN significantly contributes to morphological, physiological, and pathogenic differentiation inM. oryzaeby fostering cross-talk between multiple pathways.