Chemotaxonomic Profiling of Canadian Alternaria Populations Using High-Resolution Mass Spectrometry.

Area of Science:

• Mycology
• Food Safety
• Metabolomics

Background:

• * Alternaria species are widespread plant pathogens causing food spoilage and producing harmful secondary metabolites.
• * Accurate species-level taxonomy and differentiation of toxigenic potential in Alternaria are critical food safety challenges.
• * Current DNA sequencing methods lack reliability for distinguishing toxigenic Alternaria strains.

Purpose of the Study:

• * To identify the species of Alternaria present in Canada.
• * To characterize the secondary metabolites produced by these fungal strains.
• * To improve the chemotaxonomic classification of Canadian Alternaria populations.

Main Methods:

• * Metabolomic profiling of 128 Canadian Alternaria strains using liquid chromatography-high-resolution mass spectrometry (LC-HRMS).
• * Chemotaxonomic analysis employing principal component analysis (PCA) and k-means clustering.
• * Identification of distinguishing secondary metabolites, including tenuazonic acid, phomapyrones, and altenuene.

Main Results:

• * Four distinct populations, or chemotypes, of Alternaria were identified among the Canadian strains.
• * Key secondary metabolites like tenuazonic acid, phomapyrones, and altenuene were identified as significant distinguishing markers.
• * Alternaria infectoria was successfully identified as a distinct population through metabolomic analysis.

Conclusions:

• * Metabolomic profiling provides a robust method for chemotaxonomic classification of Alternaria species.
• * Identified chemotypes and their associated metabolites offer insights into fungal contamination risks in food.
• * While metabolomics aids in classification, further methods may be needed for complete species-level identification of all Alternaria groups.