Differences in Behavior During Early Nectarine Infection Among Main Monilinia spp. Causing Brown Rot.

Abstract

Brown rot is a disease that affects stone and pome fruit crops worldwide. It is caused by fungal members of the genus Monilinia, mainly M. fructicola, M. laxa and M. fructigena. This study presents evidence that, despite having a very similar battery of Cell Wall Degrading Enzymes (CWDEs), the three species behave differently during the early stages of infection, suggesting differences at the regulatory level, which could also explain the differences in host preference among the three species. We have shown that M. fructicola infection is accelerated by red light, and the first symptoms appear much earlier than in darkness or in the other two species. The overexpression of genes encoding for CAZymes such as pme3, pme2, pg1, cel1, pnl1 and pnl2, as well as the necrosis factor nep2, can be associated with the etiology of Monilinia spp. In addition, we found that nep2 in M. fructigena lacks binding sites in its promoter sequence for the White-Collar Complex (WCC), which is the major transcription factor responsible for regulating photo-reception processes in fungi. Finally, we found that AlphaFold models of the NEP1-like proteins (NLPs) present on the three Monilinia species predict proteins with a very high degree of similarity.