Metabolite profiling reveals overexpression of the global regulator, MoLAEA leads to increased synthesis of metabolites in Magnaporthe oryzae

Abstract Aims To study the altered metabolic pathways and metabolites produced in overexpression and knockdown mutants of a global regulator named MoLAEA, which was recently found to regulate the expression of the genes involved in secondary metabolism in one of the most destructive plant pathogens, Magnaporthe oryzae. Methods and Results Mass spectrometry-based global untargeted metabolomic profiling was used to identify altered metabolites. Metabolites were extracted from the mutant strains of MoLAEA using two extraction methods viz., aqueous and organic extraction and data acquired using liquid chromatography–tandem mass spectrometry (LC–MS/MS) in positive and negative polarities. Levels of metabolites involved in various biological pathways such as amino acid as well as polyamine biosynthesis, fatty acid and pyrimidine metabolism showed a remarkable change in the mutant strains. Interestingly, metabolites involved in stress responses were produced in higher quantities in the overexpression strain, whereas certain overproduced metabolites were associated with distinctive phenotypic changes in the overexpression strain compared with the wild type. Further, the expression of several genes involved in the stress responses was found to have higher expression in the overexpression strain. Conclusions The global regulator MoLAEA is involved in secondary metabolism in the plant pathogen M. oryzae such that the mutant strains showed an altered level of several metabolites involved in the biosynthesis pathways compared with the wild type. Also, metabolites involved in stress responses were overproduced in the overexpression strain and this can be seen in the higher growth in media amended with stress-inducing agents or a higher expression of genes involved in stress response in the overexpression strain compared with the wild type. Significance and Impact of the Study This is the first report of metabolite profiling relative to the global regulation of secondary metabolism in M. oryzae, where secondary metabolism is poorly understood. It opens up avenues for more relevant investigations on the genetic regulation of several of the metabolites found in the analysis, which have not been previously characterized in M. oryzae.