Project description:Sugarcane holds substantial agricultural and industrial importance in Brazil and worldwide, primarily due to its use in biofuel production and for a range of biomolecules of diverse biochemical applications. The drive towards sustainable agricultural practices has fostered the interest in the exploration of bioproducts to reduce the dependence on agrochemicals. In this context, microbial volatile organic compounds (VOCs) have emerged as potential biofungicides, offering several advantages over conventional chemical treatments. This study focused on evaluating their antagonistic potential against Sporisorium scitamineum, the causative agent of sugarcane smut disease, and investigated the molecular mechanisms underlying their inhibitory effects. Two Pseudomonas bacterial strains isolated from sugarcane roots exhibited remarkable antagonistic activity against S. scitamineum. Notably, ITA P2F2 completely inhibited the growth of the phytopathogen and was identified as a novel species within the Pseudomonas genus. A total of 63 VOCs were identified from both bacterial isolates, with eight showing inhibitory activity against the phytopathogen. Transcriptomic analyses revealed significant changes in gene expression of S. scitamineum when exposed to VOCs from ITA P2F2, including the downregulation of genes involved in central metabolic pathways, such as carbohydrate metabolism and fatty acid β-oxidation, and the upregulation of genes associated with DNA repair. Potential DNA damage caused by the VOCs was further evidenced through temporal analysis using Fourier Transform Infrared (FTIR) spectroscopy. Additionally, electron microscopy analysis showed structural damage to the fungal hyphae after VOCs exposure. This multidisciplinary study is the first to investigate the inhibition of S. scitamineum using VOCs. Our findings contribute to the molecular understanding of these signaling molecules and highlight their potential as promising bioproducts to replace conventional agrochemicals in the control of sugarcane pathogens.
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.
