Vacuolar ATPase subunit H regulates growth development and pathogenicity of Penicillium digitatum

Abstract

The vacuolar H+-ATPase(V-ATPase) plays a role in the maintenance of intracellular pH homeostasis. In this study, the function of the vacuolar ATPase subunit H (VmaH) in Penicillium digitatum was characterized through RNA interference (RNAi) and overexpression technology, and the underlying mechanisms were further explored by physiological and transcriptomical analyses. The results showed that silencing the VmaH gene reduced cell growth and pathogenicity of P. digitatum. Meanwhile, VmaH gene silencing increased vacuolar pH and decreased extracellular pH. The cell morphology was significantly altered in the VmaH-silenced mutant (si14). Furthermore, silencing the VmaH gene inhibited the expression of transport genes in cell membrane and interfered with nutrient metabolic processing–including glucose, amino acid, and lipid metabolisms. The disorder of nutrient metabolism in si14 reduced the biosynthesis of the main components in cell wall and cell membrane and also reduced gene transcription activity in TCA cycle and mitochondrial respiratory chain (MRC). The results showed that the superoxide anion (O2-.) and hydrogen peroxide (H2O2) in si14 were significantly increased along with alteration of the MAPK signaling pathway, ultimately leading to cell apoptosis of the pathogens accompanied by a significant up-regulation of metacaspase-1. Moreover, silencing VmaH inhibited cell wall degrading enzymes (CWDEs) and greatly down-regulated the gene encoding ACC deaminase, indicating weakened pathogenicity. We conclude VmaH plays an important role in pathogen growth and host infection, which we expect will be helpful in the search for new drug targets for P. digitatum infections.