Proteins Associated with Oxidative Burst and Cell Wall Strengthening Accumulate During Citrus-Xanthomonas Non-Host Interaction

Abstract

Citrus proteome changes at 8 and 48 h post inoculation (hpi) were analysed by both 2D gel electrophoresis and nano-LC-MS/MS proteomic approaches during interaction with Xanthomonas axonopodis pv. citri (Xac) and Xanthomonas oryzae pv. oryzae (Xoo) as host and non-host pathogens, respectively. A total of 256 proteins, 72 at 8 hpi and 184 at 48 hpi, differentially accumulated during citrus-Xanthomonas interaction. Of these, 67 and 115 proteins were specific to Xac and Xoo interaction, respectively. In addition, 64 proteins, 10 at 8 hpi and 54 at 48 hpi, variedly accumulated during both the interactions. Proteins related to photosynthesis, carbohydrate metabolism and protein synthesis were in low abundance during both the interactions resulting in reduced rate of photosynthesis. Proteins related to defence response, cell wall (CW) strengthening, lignin deposition and generation of reactive oxygen species (ROS) were in high abundance only during Xoo interaction. Whereas, during Xac interaction, proteins involved in antioxidant metabolism and CW loosening and/or elongation were in high abundance. The precise increase in abundance of these proteins during non-host interaction suggested an important role for CW fortification and ROS accumulation in non-host resistance in plants.