Isobaric tags for relative and absolute quantification-based proteomic analysis of defense responses triggered by the fungal pathogen Fusarium graminearum in wheat

Fusarium head blight (FHB) is a devastating disease worldwide that is predominantly caused by the fungal pathogen Fusarium graminearum. The aim of this work was to study differentially abundant protein species of near-isogenic lines A061-3 and A061-4 with the final goal of elucidating the molecular mechanisms of their differential resistance to F. graminearum. The objectives were accomplished using isobaric tags for relative and absolute quantification (iTRAQ) with mass spectrometry (MS). Lines A061-3 and A061-4 were resistant and susceptible to F. graminearum, respectively. At four post-inoculation points, 11,070 protein species were identified, of which 762 were differentially abundant. Gene Ontology enrichment analysis showed that most differentially abundant protein species participated in 18 biological processes after inoculation. Further analysis demonstrated that crucial metabolic pathways like plant-pathogen interaction had increased abundance. Real-time quantitative PCR (qRT-PCR) analysis revealed increased gene products of eight selected genes in plant pathogen interaction. This investigation provides a basic bioinformatics-based characterization of differentially abundant protein species during early stages against F. graminearum. Significance: FHB leads to severe yield loss and reduction in grain quality in wheat and other small grain cereals. Although extensive studies have focused on wheat resistance against F. graminearum, the molecular mechanism of FHB resistance in wheat remains to be further elucidated. In the present study, Kyoto Encyclopedia of Genes and Genomes analysis indicated that ten pathways were putatively associated with FHB resistance. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) showed that a valuable set of differentially abundant protein species including pathogenesis-related protein species were identified for further discovery of candidate genes for FHB resistance. This investigation provides new insights into the molecular mechanisms associated with FHB resistance and as well as a foundation for future studies.