Deciphering Molecular Determinants Underlying Penicillium digitatum's Response to Biological and Chemical Antifungal Agents by Tandem Mass Tag (TMT)-Based High-Resolution LC-MS/MS.

Lucía Citores,Mariangela Valletta,José Miguel Ferreras,Rosita Russo,Rosario Iglesias,Vikram Pratap Singh,Angela Chambery,Paolo Vincenzo Pedone

doi:10.3390/ijms23020680

Abstract

Penicillium digitatum is a widespread pathogen responsible for the postharvest decay of citrus, one of the most economically important crops worldwide. Currently, chemical fungicides are still the main strategy to control the green mould disease caused by the fungus. However, the increasing selection and proliferation of fungicide-resistant strains require more efforts to explore new alternatives acting via new or unexplored mechanisms for postharvest disease management. To date, several non-chemical compounds have been investigated for the control of fungal pathogens. In this scenario, understanding the molecular determinants underlying P. digitatum’s response to biological and chemical antifungals may help in the development of safer and more effective non-chemical control methods. In this work, a proteomic approach based on isobaric labelling and a nanoLC tandem mass spectrometry approach was used to investigate molecular changes associated with P. digitatum’s response to treatments with α-sarcin and beetin 27 (BE27), two proteins endowed with antifungal activity. The outcomes of treatments with these biological agents were then compared with those triggered by the commonly used chemical fungicide thiabendazole (TBZ). Our results showed that differentially expressed proteins mainly include cell wall-degrading enzymes, proteins involved in stress response, antioxidant and detoxification mechanisms and metabolic processes such as thiamine biosynthesis. Interestingly, specific modulations in response to protein toxins treatments were observed for a subset of proteins. Deciphering the inhibitory mechanisms of biofungicides and chemical compounds, together with understanding their effects on the fungal physiology, will provide a new direction for improving the efficacy of novel antifungal formulations and developing new control strategies.

Highlights

Citrus fruits, comprising oranges, grapefruit, mandarins, limes and lemons, are among the most widespread fruit crop worldwide, highly enriched with components beneficial to human health
beetin 27 (BE27) treatments was observed for a subset of proteins, paving the way to understanding the molecular determinants underlying P. digitatum response 3toof biologica and synthetic antifungal agents
A label-free quantitative proteomic analysis was performed on Fusarium oxysporum f. sp. cucumerinum mycelia following treatment with canthin-6-one, an alkaloid compound extracted from Ailanthus altissima, with the aim of investigating the molecular mechanisms underlying the antifungal properties of this molecule [15]

Summary

Introduction

Citrus fruits (genus Citrus in family Rutaceae), comprising oranges, grapefruit, mandarins, limes and lemons, are among the most widespread fruit crop worldwide, highly enriched with components beneficial to human health. The great economic value of the citrus fruits market is based on properties that largely rely on factors affecting both external and internal quality. The main causes of rejects include weight loss, presence of bruises and cuts, symptoms of mould and decay and colour changes. The green mould and blue mould, caused by Penicillium digitatum and Penicillium italicum, respectively, represent the two most important diseases in all citrus production during fruits postharvest handling procedures [3,4]. The postharvest green mould is the main factor affecting citrus fruit decay, leading to huge economic losses worldwide every year and accounting for up to 90% of the total citrus postharvest losses, especially in subtropical climates [4]

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