Methodological evaluation of 2-DE to study root proteomics during nematode infection in cotton and coffee plants

The identification of plant proteins expressed in response to phytopathogens is a remaining challenge to proteome methodology. Proteomic methods, such as electrophoresis and mass spectrometry have been extensively used for protein differential expression studies in several plants including Arabidopsis thaliana, rice, and wheat. However, in coffee (Coffea canephora) and cotton (Gossypium hirsutum), bidimensional electrophoresis (2-DE) analysis has been rarely employed. Moreover, global protein expression in both agricultural plants in response to biotic stress conditions had not been reported until now. In this study, Meloidogyne paranaensis and M. incognita, two devastating phytonematodes for numerous crop cultures, were used to infect resistant genotypes of coffee and cotton plants. The protein expression of infected- and non-infected roots were evaluated by 2-DE following in silico experiments. Additionally, gels were stained with silver nitrate and/or Coomassie brilliant blue in order to obtain an optimized method for proteomic analysis of plant-nematode interaction. The 2-DE analysis revealed an enhanced number of protein spots, as well as differentially expressed proteins, when Coomassie brilliant blue was used. The results obtained here could be extended to other plant species, providing valuable information to root-nematode interactions.