Antagonistic manipulation of ER-protein quality control between biotrophic pathogenic fungi and host induced defense

Abstract

The interaction of plants with pathogens during infection is a multifaceted process involving various molecules deriving from both partners. A current goal in combating pathogen virulence is to induce plant resistance using environmentally friendly compounds. Here, we show that chitosan-based nanoparticles loaded with the defense hormone salicylic acid, can efficiently activate defense responses and reactive oxygen species (ROS) production and PATHOGENESIS RELATED-1 (PR1) expression in Arabidopsis thaliana leaves, and reduce conidial germination of the biotrophic pathogenic fungus Podosphaera xanthii. Transcriptomic and proteomic analyses identified immune response-related upregulated transcripts and proteins after nanoparticle application, highlighting the Leucine Rich Repeat (LRR)-, Systemic Acquired Resistance (SAR)-, and glutathione-related protein groups. Examination of P. xanthii during infection at control conditions, identified ribosomal, hydrolase-related, putative secreted and effector proteins, while nanoparticle application significantly downregulated their expression. An in-depth investigation of the highly expressed proteins in P. xanthii and Arabidopsis revealed the involvement of components of endoplasmic reticulum protein quality control (ERQC) in the pathogen-host interaction. The RPS27A effector protein was identified in fungal virulence, while endoplasmic reticulum (ER) protein processing- and glycosyltransferase-related proteins were implicated in plant's induced defense response following nanoparticle application. Overall, these findings demonstrate that the ERQC is dynamically manipulated by both the pathogen for efficient virulence and by elicitors for plant induced defense.

Keywords

• Chitosan nanoparticles
• Induced defense
• Biotrophic pathogen
• Endoplasmic reticulum protein quality control
• Fungal effectors