Positively Regulate Development, Infection Structure Differentiation and Pathogenicity in , Causal Agent of Pear Black Spot.

Calcium/calmodulin-dependent protein kinase (CaMK), a key downstream target protein in the Ca signaling pathway of eukaryotes, plays an important regulatory role in the growth, development and pathogenicity of plant fungi. Three AaCaMKs (AaCaMK1, AaCaMK2 and AaCaMK3) with conserved PKC_like superfamily domains, ATP binding sites and ACT sites have been cloned from , However, their regulatory mechanism in remains unclear. In this study, the function of the in the development, infection structure differentiation and pathogenicity of was elucidated through targeted gene disruption. The single disruption of had no impact on the vegetative growth and spore morphology but significantly influenced hyphae growth, sporulation, biomass accumulation and melanin biosynthesis. Further expression analysis revealed that the were up-regulated during the infection structure differentiation of on hydrophobic and pear wax substrates. In vitro and in vivo analysis further revealed that the deletion of a single gene significantly reduced the conidial germination, appressorium formation and infection hyphae formation. In addition, pharmacological analysis confirmed that the CaMK specific inhibitor, KN93, inhibited conidial germination and appressorium formation in . Meanwhile, the genes deficiency significantly reduced the pathogenicity. These results demonstrate that regulate the development, infection structure differentiation and pathogenicity of and provide potential targets for new effective fungicides.