Proteome analysis of cucumber responses to Pseudoperonospora cubensis infection

Abstract

Downy mildew is one of the most prevalent diseases that cause destructive damages to the production of cucumber worldwide. To understand the regulation mechanism underlying the responses of cucumber leaves to P. cubensis infection, a proteomic approach was used to profile protein variations in cucumber leaves during a incubation period of up to 72 h. Differentially accumulated proteins (DAPs) at different time points after inoculation were investigated. A total of 90 DAP spots were identified using an integrated approach involving two-dimensional gel electrophoresis and MALDI-TOF-TOF mass spectrometer. Functional classification showed that most DAPs were putatively involved in metabolic reaction, transportation, protein folding, proteolysis, cell proliferation, photosynthesis, glucose metabolism, translation elongation, damage response, and other closely related biological processes. Several antioxidants, such as Cu/Zn-superoxide dismutase and 2-cysteine peroxiredoxins, were significantly up-regulated under P. cubensis infection. These antioxidants may play roles in regulating potentially harmful reactive oxygen species under pathogen infections. Furthermore, changes in the photosynthetical system-related proteins and heat shock proteins were observed under P. cubensis infection. Our data provides fundamental resources for identifying candidate proteins and metabolic pathways involved in the responses of cucumber plants to P. cubensis infection.