Comprehensive Analysis of the Alternaria Mycobolome Using Mass Spectrometry Based Metabolomics.

Marina Gotthardt,Thomas Hofmann,Oliver Frank,Michael Rychlik,Richard Hammerl,Philippe Schmitt‐Kopplin,Basem Kanawati,Stefan Asam,Frank Schmidt

doi:10.1002/mnfr.201900558

Abstract

Alternaria fungi are widely distributed plant pathogens infecting grains and vegetables and causing major harvest losses in the field and during postharvest storage. Besides, consumers are endangered by the formation of toxic secondary metabolites. Some of these secondary metabolites are chemically characterized as mycotoxins, but the majority of the Alternaria mycobolome still remains unknown. Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) and LC-MS/MS are combined for the non-targeted and targeted analysis of the metabolome of three A.alternata isolates and one A.solani isolate. Due to the ultra-high resolution of FTICR-MS, unique molecular formulae are assigned to measured m/z signals. The molecular formulae are matched to entries of the databases Antibase and Kyoto Encyclopedia of Genes and Genomes. The non-targeted analysis of the fungal extracts reveals variations in the secondary metabolite profile of A.alternata and A.solani. Differences in the biosynthesis of dibenzo-α-pyrones, perylene quinones, tentoxin, and tenuazonic acid of the A.alternata and A.solani isolates are determined applying targeted LC-MS/MS. FTICR-MS analyses reveal clear differences in the metabolic profile of the A.solani and the A.alternata isolates.

Highlights

Fungi of the genus Alternaria are widely distributed on seeds, plants, animals, in the soil, and in the atmosphere.[1]
The fungi were cultivated in a chemical defined liquid medium consisting of salts and glucose facilitating the detection of metabolites solely biosynthesized by Alternaria
Metabolic profiling is mainly performed by growing the fungi on solid media due to a higher quantity and a higher number of produced metabolites,[29] In 2018, Zwickel et al performed a study on the metabolic profiles of different Alternaria species grown on rice,[31] After the cultivation, the mycotoxins were laboriously extracted using a mixture of acetonitrile/water/acetic acid.[59]

Summary

Introduction

Fungi of the genus Alternaria are widely distributed on seeds, plants, animals, in the soil, and in the atmosphere.[1]. Over 70 different secondary metabolites are described in the literature and more than 30 exhibit toxicological potential. [9]

Methods

Results

Conclusion