Inhibition of the Growth and Development of Sclerotinia sclerotiorum (Lib.) De Bary by Combining Azoxystrobin, Penicillium chrysogenum VKM F-4876d, and Bacillus Strains

Vera V Yaderets,Kseniya S Petrova,Nataliya V Karpova,Elena V Glagoleva,Vakhtang V Dzhavakhiya,Alexander I Ovchinnikov

doi:10.3390/agronomy11122520

Abstract

Sclerotinia sclerotiorum (Lib.) de Bary is a plant pathogen with a wide host range, which causes significant yield and storage losses of edible roots and other plant products. Due to its ability to sclerotia formation, the efficient control of this pathogen is complicated. The study of five Bacillus strains (B. subtilis VKM B-3154D, VKM B-3155D, VKM B-3505D, VKM B-2998D, and B. amyloliquefaciens VKM B-3153D) showed their ability to produce polyene antibiotics suppressing the growth and development of plant pathogenic fungi. The maximum concentration of polyene compounds was revealed for B. subtilis VKM B-2998D. A high in vitro antifungal activity of a dry mycelium biomass (DMP) of Penicillium chrysogenum VKM F-4876D, B. subtilis VKM B-2998D, and their combination has been demonstrated in relation to S. sclerotiorum. A combined application of DMP (0.3 g/L) and azoxystrobin at low dosage (2.5 mg/L) showed a high suppressing activity towards S. sclerotiorum (100% growth inhibition) including inhibition of a sclerotia formation that may be useful for the development of efficient methods of crop protection against this plant pathogen. A high performance liquid chromatography (HPLC) analysis of DMP revealed the presence of mevastatin suggesting the mechanism of the DMP antifungal activity is based on the blocking of the ergosterol (the main component of fungal cell walls) biosynthesis. The results of the study provide a prerequisite to the development of biopreparations to control S. sclerotiorum, whose use may provide a reduction of concentrations of fungicides used in agriculture and the corresponding reduction of their negative xenobiotic impact on the environment and recovery of the ecological balance in the soil.

Highlights

Sclerotinia sclerotiorum (Lib.) de Bary is a universal necrotrophic plant pathogen infecting aboveground or underground parts of more than 500 plant species from 75 families [1,2]
A high in vitro antifungal activity of a dry mycelium biomass (DMP) of Penicillium chrysogenum VKM F-4876D, B. subtilis VKM B-2998D, and their combination has been demonstrated in relation to S. sclerotiorum
A combined application of DMP (0.3 g/L) and azoxystrobin at low dosage (2.5 mg/L) showed a high suppressing activity towards S. sclerotiorum (100% growth inhibition) including inhibition of a sclerotia formation that may be useful for the development of efficient methods of crop protection against this plant pathogen

Summary

Introduction

Sclerotinia sclerotiorum (Lib.) de Bary is a universal necrotrophic plant pathogen infecting aboveground or underground parts of more than 500 plant species from 75 families [1,2]. Due to the ability of S. sclerotiorum to synthesize oxalic acid [1,10] and lytic enzymes, such as cellulase, hemicellulase, pectinase, and polygalacturonase [1,11,12], it provokes the development of various rots of roots, stems, and other plant organs characterized by a formation of soft watery areas with well-distinguished edges [13,14] Another typical sign of infection of plants or edible roots with S. sclerotiorum (especially during a storage period) is the development of a white or light-grey scurf with cotton-like mycelium aggregations [13,15]. A wide range of host plants infected with S. sclerotiorum significantly limits the efficiency of various agrotechnical approaches (crop rotation, soil treatments.) intended to minimize pathogen development and to reduce disease-associated economic losses [19,20]

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