Synergistic Antifungal Activity of Graphene Oxide and Fungicides against Fusarium Head Blight In Vitro and In Vivo.

Xiuping Wang,Xuejuan Shi,Caihong Cheng,Jun Li,Xiaoduo Gao,Fei Peng,Lina Chen

doi:10.3390/nano11092393

Abstract

Plant pathogens constantly develop resistance to antimicrobial agents, and this poses great challenges to plant protection. Therefore, there is a pressing need to search for new antimicrobials. The combined use of antimicrobial agents with different antifungal mechanisms has been recognized as a promising approach to manage plant diseases. Graphene oxide (GO) is a newly emerging and highly promising antimicrobial agent against various plant pathogens in agricultural science. In this study, the inhibitory activity of GO combined with fungicides (Mancozeb, Cyproconazol and Difenoconazole) against Fusarium graminearum was investigated in vivo and in vitro. The results revealed that the combination of GO and fungicides has significant synergistic inhibitory effects on the mycelial growth, mycelial biomass and spore germination of F. graminearum relative to single fungicides. The magnitude of synergy was found to depend on the ratio of GO and fungicide in the composite. In field tests, GO–fungicides could significantly reduce the disease incidence and disease severity, exhibiting a significantly improved control efficacy on F. graminearum. The strong synergistic activity of GO with existing fungicides demonstrates the great application potential of GO in pest management.

Highlights

Considering the cost and feasibility of practical application of Graphene oxide (GO)–fungicides, we chose Man–GO at 8:2 and Cyp–GO and Dif–GO at 5:5 as the best combinations for subsequent characterization and antifungal activity analysis. These results confirmed the findings of Yang et al, who claimed that the antifungal activity of two and more fungicides can be synergized only when these fungicides are combined with the appropriate ratio [28]
The present study provides evidence that the combination of GO with fungicides can bring about a synergistic inhibitory effect on F. graminearum in vitro and in vivo, with the magnitude of synergy depending on the ratio of GO and fungicide in the composite
At the optimal combination ratio, the fungicide adsorbed on the surface of GO can achieve the highest adsorption capacity and dispersibility

Summary

Introduction

Recent studies have revealed that GO has a broad spectrum of bactericidal activity, and can significantly inhibit the growth of both Gram-negative and Gram-positive bacteria [4,5]. As a newly emerging antimicrobial agent against plant pathogenic bacteria and fungi, GO has attracted great research interests and is believed to have great application potential in agricultural production [6,7,8,9]. GO can strongly inhibit the mycelial growth and spore germination of various plant fungal pathogens, such as Fusarium graminearum, Fusarium poaea and Fusarium oxysporum [9]. The high antibacterial activity of GO against plant pathogens makes it a promising candidate for the control of phytopathogens

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