Project description:Dimorphic fungi have the ability to change morphology during their lifecycle, a crucial feature for the establishment of infection and fungal growth and development in planta. Life cycle of the dimorphic sugarcane smut fungi, Sporisorium scitamineum, involves recognition and mating of compatible saprophytic yeast-like haploid sporidia (MAT-1 and MAT-2) that upon fusion, develop into infective dikaryotic mycelia. Although the dimorphic transition is intrinsically linked with the pathogenicity and virulence of S. scitamineum, it has never been studied using a proteomics approach. In the present study, an iTRAQ-based comparative proteomic analysis of three distinct stages covering the dimorphic transition period - haploid sporidial stage (MAT-1 and MAT-2) to the transition phase (24 hours post co-culturing (hpc)) and dikaryotic mycelial stage (48 hpc) was carried out. Functional categorization showed that the most altered biological processes were energy production, primary metabolism especially carbohydrate, amino acid, fatty acid, followed by translation, post-translation and protein turnover. The identified proteins could be grouped into 8 distinct clusters with different trends in abundance. Enrichment analysis of the clusters showed that biological processes related to energy production through oxidative phosphorylation, citrate cycle, and β-oxidation, transcription, translation and redox homeostasis were specifically altered. In addition, an overall downregulation of carbohydrate metabolism and reprogrammed amino acid metabolism were observed. Several differentially abundant proteins (DAPs), especially in the dikaryotic mycelial stage were predicted as effectors. Taken together, key molecular mechanisms underpinning the dimorphic transition in S. scitamineum at the proteome level were highlighted. A catalogue of stage-specific and dimorphic transition-associated -proteins and potential effectors identified herein are potential candidates for defective mutant screening to elucidate their functional role in the dimorphic transition and pathogenicity in S. scitamineum.
Project description:There are two mating types, “+” and “-” strains in S. scitamineum. Generally, dikaryote cells are formed after fussion of the germ turbs from both mating type strains and filamentation (filamentous growth) with infection potential occur afterward. By introducing bE2 gene and/or orther related genes, derived from the opposite mating type strain JG36, haploid mutants with filamentation characteristics were generated, including M6,M8,M9 and M10. Among these are 446 genes that were found in both filamentous haploid strains, including 237 genes up-regulated and 209 genes down-regulated. The up-regulated genes were mainly enriched in amino acid biosynthesis, starch and sucrose metabolism, secondary metabolite biosynthesis, and pentose phosphate pathways. Down-regulated expression genes are mainly enriched in fatty acid synthesis and metabolism, homologous recombination, peroxides, biosynthesis of unsaturated fatty acids, ubiquitin-mediated protein hydrolysis and other metabolic pathways. Several MAP kinases and protein kinases were up- or down-regulated in the filamentous haploid.
