Raman microscopy tracks maturity of melanin intermediates in Botrytis cinerea, a plant pathogen

Area of Science:

• Biophysics
• Mycology
• Spectroscopy

Background:

• Botrytis cinerea is a significant fungal plant pathogen impacting agriculture.
• Understanding its structure and chemical composition is crucial for disease management.
• Melanin synthesis is a key pathway in fungal virulence and protection.

Purpose of the Study:

• To characterize the structure and chemical composition of Botrytis cinerea conidiophores and hyphae using Raman microscopy.
• To computationally validate spectral interpretations using density functional theory (DFT) for fungal components and melanin precursors.
• To investigate the distribution of structural elements, pigments, and proteins within the fungus.

Main Methods:

• Raman microscopy was employed to analyze the chemical fingerprint of B. cinerea.
• Density functional theory (DFT) calculations were performed to compute Raman tensors for chitin, glycopeptides, and naphthalene derivatives.
• Spectral data were correlated with microscopy images to map molecular distributions.

Main Results:

• Distinct Raman spectral signatures were identified for different fungal structures and components.
• DFT calculations provided validation for interpreting experimental spectra, particularly for melanin precursors.
• Differences in the distribution of structural components, pigments, and proteins were observed between spores and hyphae.

Conclusions:

• The study elucidates the chemical composition of B. cinerea, highlighting the role of naphthalene-based compounds in melanin synthesis.
• Findings suggest convergent evolution in secondary metabolite production among plant pathogenic fungi.
• Pre-resonant Raman monitoring of melanin precursors offers a potential tool for assessing B. cinerea population biology in agricultural settings.