Proteomic Analysis of the Secretory Proteins from Phytophthora infestans under Nitrogen Deficiency using Label-free LC-MS

Phytophthora infestans causes the late blight disease in potato, and its effectors have a potential role in its pathogenicity. Nitrogen is a key nutrient source affecting the growth and development of microbiota. Differentially expressed proteins secreted by the P. infestans strain NOD-1 were analyzed using label-free liquid chromatography-mass spectrometry quantitative proteomics in a complete medium or under nitrogen-deficient conditions to understand whether nitrogen stress promoted the secretion of more pathogenic proteins by P. infestans. A total of 5615 unique peptides and 1188 proteins were identified. Moreover, 93 differentially expressed proteins (containing signal peptides of Crinkling and necrosis-inducing protein and Arginine-X-leucine-arginine) and 28 specific proteins (localized extracellularly, in the cytoplasm, and in the plasma membrane) were detected under nitrogen-deficient conditions. Furthermore, 27 important effectors (mainly apoplastic and cytoplasmic), which had a potential role in the infection process, were screened. This study showed that the pathogenicity of P. infestans was enhanced under nitrogen-deficient conditions through the expression of effectors, particularly the cytoplasmic effectors. (C) 2018 Friends Science Publishers