Proteomic analysis of the tripartite interaction between black pepper, Trichoderma harzianum and Phytophthora capsici provides insights into induced systemic resistance mediated by Trichoderma spp.

Trichoderma harzianum (MTCC5179) is the biocontrol agent in the black pepper (Piper nigrum.L) production system against the destructive pathogen Phytophthora capsici which causes foot and root rot. We employed label-free quantitative proteomics to study the T. harzianum mediated induced systemic response in this system. We studied the defence response in leaves in T. harziznum primed plant roots which are also infected with P. capsici. The pattern of interactions was studied as black pepper x T. harzianum (two-way), black pepper x P. capsici (two-way) and black pepper x T. harzianum x P. capsici (three-way). The proteins induced only in the three-way interaction were identified as Trichoderma induced resistance proteins. Eighteen reactive oxygen species-related proteins and 22 defence-related proteins were identified as marker proteins. Apart from these groups, the ethylene synthesis, isoflavanoid pathway and lignin synthesis proteins were found to be enhanced. We report the early induced systemic resistance in leaves after Trichoderma priming at roots (72, and 96h after interaction) against Phytophthora capsici after 12 and 24h of infection at roots. The peptides/proteins from this study will serve as important marker peptides/proteins for the induced systemic resistance in plants by Trichoderma.