Multiplex real-time PCR assay for simultaneous detection of Omphalotus guepiniformis and Lentinula edodes

Loop-mediated isothermal amplification (LAMP) for rapid and easy identification of Omphalotus japonicus

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We constructed a LAMP to specifically detect toxic Omphalotus japonicus mushrooms.

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The process took less than 2 h from DNA extraction to detection.

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Results were determined visually using fluorescent detection reagents.

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This method can be used to identify food poisoning caused by O. japonicus.

Omphalotus japonicus is a major toxic mushroom in Japan. When food poisoning caused by O. japonicus occurs, quick and accurate identification using a method that does not rely on morphological discrimination is required. Because the loop-mediated isothermal amplification (LAMP) method meets these requirements, we developed a LAMP method for detecting O. japonicus. Amplification occurred within 60 min, and the presence or absence of O. japonicus was confirmed within 2 h, including the DNA extraction protocol. The LAMP method did not show cross-reactivity with 13 species of edible mushrooms, had high specificity toward O. japonicus, and had sufficient detection sensitivity even in a mixed mushroom sample containing 1% O. japonicus. Additionally, O. japonicus could be detected in simulated food poisoning samples of heated and digested mushrooms, and in actual food poisoning residual samples.

De novo genome assembly of the bioluminescent mushroom Omphalotus guepiniiformis reveals an Omphalotus-specific lineage of the luciferase gene block

Omphalotus guepiniiformis, a bioluminescent mushroom species, is a source of the potentially valuable anticancer chemical. To provide genome information, we de novo assembled the high-quality O. guepiniiformis genome using two Next-Generation sequencing techniques, PacBio and Illumina sequencing. Our draft O. guepiniiformis genome comprises 42.5 Mbp of sequence with only 80 contigs and an N50 sequence length of over 1 Mbp. There were 15,554 predicted coding genes, and 7693 genes were functionally annotated with Gene Ontology terms. We performed a genomic study focusing on mushroom bioluminescent pathway cluster genes by comparing 17 luminescent and 23 non-luminescent Agaricales species belonging to 23 genera. Synteny analysis of genomic regions near the luminescent pathway cluster genes inferred that the Omphalotus lineage was genus-specific. In summary, our de novo assembled O. guepiniiformis genome provides significant biological insights into this organism, including the evolution of the luciferase gene block, and forms the basis for future analyses.

Rapid identification of Gloriosa superba and Colchicum autumnale by melting curve analysis: application to a suicide case involving massive ingestion of G. superba

The plant species Gloriosa superba and Colchicum autumnale produce extremely poisonous colchicine as a major toxic metabolite. Almost all previous studies on colchicine poisoning have focused on drug analysis and clinical and pathological aspects. In this study, we developed a rapid, highly sensitive method to identify G. superba and C. autumnale. This method, which can distinguish between G. superba and C. autumnale using even minute amounts of plant material, is based on duplex real-time PCR in combination with melting curve analysis. To discriminate between the two genera of colchicine-containing plants, we designed new primer pairs targeting the region of the ycf15 gene, which is present in C. autumnale but not G. superba. By producing PCR amplicons with easily distinguishable melting temperatures, we were able to rapidly and accurately distinguish G. superba from C. autumnale. The new primer pairs generated no PCR amplicons from commercially available human DNA or various plant DNAs except for G. superba and C. autumnale. Sensitivity testing indicated that this assay can accurately detect less than 0.031 ng of DNA. Using our method in conjunction with colchicine drug analysis, we successfully identified G. superba in the stomach contents of a suicide victim who ingested massive quantities of a colchicine-containing plant. According to these results, duplex real-time PCR analysis is very appropriate for testing forensic samples, such as stomach contents harboring a variety of vegetables, and enables discrimination between G. superba and C. autumnale in forensic and emergency medical fields.

PCR-Based Method for the Detection of Toxic Mushrooms Causing Food-Poisoning Incidents

In this study, species-specific identification of five toxic mushrooms, Chlorophyllum molybdites, Gymnopilus junonius, Hypholoma fasciculare, Pleurocybella porrigens, and Tricholoma ustale, which have been involved in food-poisoning incidents in Japan, was investigated. Specific primer pairs targeting internal transcribed spacer (ITS) regions were designed for PCR detection. The specific amplicons were obtained from fresh, cooked, and simulated gastric fluid (SGF)-treated samples. No amplicons were detected from other mushrooms with similar morphology. Our method using one-step extraction of mushrooms allows rapid detection within 2.5 hr. It could be utilized for rapid identification or screening of toxic mushrooms.