Identification of Candidate Genes Associated with Trichothecene Biosynthesis in Fusarium graminearum Species Complex Combined with Transcriptomic and Proteomic Analysis.

The Fusarium graminearum species complex is the main causal agent of wheat head blight worldwide. Trichothecenes produced by the pathogen in infected grains have important food safety implications. Previously reported studies on trichothecene production have all focused on the conditions conducive to mycotoxin production, while the molecular mechanisms of trichothecene biosynthesis in Fusarium strains under normal or non-inducing conditions are still unclear. Here, a global analysis of the fungal gene expression of three strains using the Affymetrix Fusarium GeneChip under non-inducing conditions is reported. Differentially expressed genes were identified among strains with different trichothecene-production ability, and some novel genes associated with trichothecene biosynthesis were found by bioinformatics analysis. To verify the transcriptome results, proteomic analyses of the three strains were conducted under the same culture conditions. In total, 69 unique fungal proteins were identified in 77 protein spots. Combined with transcriptome and proteome analysis, 27 novel genes were predicted to be associated with trichothecene mycotoxin production. A protein, encoded by FGSG_01403, was found to be associated with trichothecene production via proteome analysis. Gene knock-out mutations of FGSG_01403 resulted in mutants with increased production of trichothecenes. Future functional analysis of the candidate genes identified in this study may reveal new insights into the negative regulation of trichothecene production in the Fusarium graminearum species complex.

Species Composition and Toxigenic Potential of Fusarium Isolates Causing Fruit Rot of Sweet Pepper in China.

Apart from causing serious yield losses, various kinds of mycotoxins may be accumulated in plant tissues infected by Fusarium strains. Fusarium mycotoxin contamination is one of the most important concerns in the food safety field nowadays. However, limited information on the causal agents, etiology, and mycotoxin production of this disease is available on pepper in China. This research was conducted to identify the Fusarium species causing pepper fruit rot and analyze their toxigenic potential in China. Forty-two Fusarium strains obtained from diseased pepper from six provinces were identified as F. equiseti (27 strains), F. solani (10 strains), F.fujikuroi (five strains). This is the first report of F. equiseti, F. solani and F. fujikuroi associated with pepper fruit rot in China, which revealed that the population structure of Fusarium species in this study was quite different from those surveyed in other countries, such as Canada and Belgium. The mycotoxin production capabilities were assessed using a well-established liquid chromatography mass spectrometry method. Out of the thirty-six target mycotoxins, fumonisins B1 and B2, fusaric acid, beauvericin, moniliformin, and nivalenol were detected in pepper tissues. Furthermore, some mycotoxins were found in non-colonized parts of sweet pepper fruit, implying migration from colonized to non-colonized parts of pepper tissues, which implied the risk of mycotoxin contamination in non-infected parts of food products.

Multi-mycotoxin analysis of animal feed and animal-derived food using LC-MS/MS system with timed and highly selective reaction monitoring.

Mycotoxins have the potential to enter the human food chain through carry-over of contaminants from feed into animal-derived products. The objective of the study was to develop a reliable and sensitive method for the analysis of 30 mycotoxins in animal feed and animal-derived food (meat, edible animal tissues, and milk) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In the study, three extraction procedures, as well as various cleanup procedures, were evaluated to select the most suitable sample preparation procedure for different sample matrices. In addition, timed and highly selective reaction monitoring on LC-MS/MS was used to filter out isobaric matrix interferences. The performance characteristics (linearity, sensitivity, recovery, precision, and specificity) of the method were determined according to Commission Decision 2002/657/EC and 401/2006/EC. The established method was successfully applied to screening of mycotoxins in animal feed and animal-derived food. The results indicated that mycotoxin contamination in feed directly influenced the presence of mycotoxin in animal-derived food. Graphical abstract Multi-mycotoxin analysis of animal feed and animal-derived food using LC-MS/MS.

Characterization of a new pathovar of Agrobacterium vitis causing banana leaf blight in China.

A new banana leaf blight was found in Nanning city, China, during a 7-year survey (2003-2009) of the bacterial diseases on banana plants. Eight bacterial strains were isolated from affected banana leaves, and identified as an intraspecific taxon of Agrobacterium vitis based on their 16S rDNA sequence similarities with those of 37 randomly selected bacterial strains registered in GenBank database. The representative strain Ag-1 was virulent on banana leaves and shared similar growth and biochemical reactions with the reference strain IAM14140 of A. vitis. The strains causing banana leaf blight were denominated as A. vitis pv. musae. The traditional A. vitis strains virulent to grapevines were proposed to be revised as A. vitis pv. vitis. This is the first record of a new type of A. vitis causing banana leaf blight in China.