sclerotinia sclerotiorum

Sclerotinia sclerotiorum (Lib.) de Bary caused white mold disease with a wide distribution worldwide. For the control of the disease, it is fundamental to understand the identification, morphology, and genetic diversity of the fungus. The objective of this study was to collect and characterize S. sclerotiorum isolates from different regions of the country. The characteristics evaluated for the mycelium characterization were: the time required for the fungus to occupy the plate; density of the formed mycelium; coloration of the colonies and mycelia growth rate. Sclerotia assessments were based on the time for the formation of the first sclerotia total number formed per plate, the format of distribution in the plate, and the shape of the sclerotia formed by the isolates. Variability was observed for colony colour, type of growth, the diameter of mycelia growth, sclerotia initiation, and number and pattern of sclerotia formation among the isolates. The evaluated populations presented wide variability for the cultural and morphological characteristics, being predominant in the whitish colonies with fast-growing habitats. The majority of isolates produced a higher number of sclerotia near the margin of the plates and with diverse formats. Phylogenetic analysis revealed that the isolates belonged to a similar group of publicly available S. sclerotiorum and were dissimilar from the group of S. minor, and S. trifolium and distinctly differ from S. nivalis group. The present study is the first evidence for morphological and genetic diversity study of S. sclerotiorum in Bangladesh. Therefore, this report contributes to more information about the morphological and genetic diversity of S. sclerotiorum and can be useful in implementing effective management strategies for the pathogen which caused white mold disease.

The stem rot disease has emerged globally as a major threat to oilseed Brassica's productivity and seed quality. The generalist causal pathogen Sclerotinia sclerotiorum (Lib.) de Bary shows large variability in their aggressiveness and pathogenicity. Revealing the pathogen's metabolic profile and signaling components in host-pathogen interaction is fundamental in understanding host resistance to the disease. In this study, the metabolites released by the pathogenic strains of S. sclerotiorum under the axenic culture have been identified using the untargeted high-resolution UPLC-QTOF-ESI-MS/MS. The analysis of the ethyl acetate extracts of the S. sclerotiorum culture revealed ten major secondary metabolites namely, sclerin, sclerotinin-B, sclerone, melanin, bostrycoidin, botcinin-D, botcinin-A, gliovirin, scleramide, and botcinic acid. The later six metabolites are being reported for the first time in the culture extract of the S. sclerotiorum pathogen. Based on the overlapping and unique informative peaks in the chromatograms, the six S. sclerotiorum strains were grouped into three major clades in the phylogenetic analysis. The clustering based on metabolic profiles does not substantiate the diversity based on morphology or virulence differences over the host. The findings of the study signified the metabolites secreted under the axenic conditions are varies based on their growth and developmental stages and may not necessarily be the determining factors for their differential aggressiveness and virulence to their host. 

Sclerotinia sclerotiorum is a necrotrophic plant pathogen causing more than 60 different disease symptoms in approximately 400 plants globally. Hence, due to this distinctive characteristic, S. sclerotiorum has been the subject of various research to comprehend its pathogenicity mechanism, including virulent genes, proteins, and metabolites. Likewise, the genomic annotation of S. sclerotiorum uncovered its remarkable potential for producing secondary metabolites, of which genome mining has additionally prompted the disclosure of these uncharacterized metabolic pathways, which might aid the pathogenicity process. To comprehend the secondary metabolites secreted by S. sclerotiorum that might be involved in its pathogenicity, a secondary metabolite-level investigation of this plant pathogen was performed. Profiling and characterizing these secondary metabolites produced during in vitro germination would increase the current knowledge of this pathogen. In this study, S. sclerotiorum secondary metabolites profile examination was conducted, utilizing the Ultra-High Resolution Qq-Time-Of-Flight mass spectrometer (UHR-QqTOF). Proficient data analysis and verification with the genomic pathways of S. sclerotiorum gave an unequivocal metabolome profile of this pathogen. Two hundred and thirty secondary metabolites were identified in all three biological replicates, and their bodily functions were identified.