Veterinary Biosciences - Research Publications
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ItemMetabolic profiling of cytotoxic steroidal saponins in five Australian Panicum species(ISOPP, 2018-09-18)Up to 500 species of Panicum (panic grasses) are recognised worldwide, of which 24 species are indigenous to Australia and nine introduced. Recently, some of the introduced summer-growing annual Panicum spp. have been identified with high prevalence across southern Australia. Certain Panicum species have also been implicated in severe outbreaks of hepatogenous photosensitization in livestock, characterized by crystal-associated cholangiohepatopathy. The causal compound(s) responsible for liver dysfunction in livestock ingesting Panicum spp. have been previously identified as steroidal saponins. Although metabolic profiling of Panicum spp. has been undertaken in the USA and NZ, the saponins implicated in toxic outbreaks in Australia have not yet been identified. In this study, fresh shoot tissue from three introduced (P. capillare,P. hillmanii and P. gilvum) and two native (P. decompositumand P. effusum) species were extracted in methanol and analysed by UPLC/QTOF mass spectrometry. The relative abundance of key steroidal saponins was determined based on specific molecular features including retention time, mass spectra and fragmentation pattern when compared to saponin analytical standards. Distinct qualitative and quantitative differences were observed in the saponin profiles of the Panicum species evaluated, including in the type, number and abundance of the saponins detected, such as protodioscin and pseudoprotodioscin.. In vitro cytotoxicity assays of shoot extracts collected from Panicumrelated photosensitization outbreaks will be performed to further identify key steroidal saponins and saponin profiles associated with hepatogenous photosensitization in grazing livestock.
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ItemIdentification of eight Panicum species in Riverina region of NSW using DNA sequence analysisDNA sequence analysis(Council of the Australasian Weed Societies/ The Weed Society of New South Wales Inc., 2018-09-12)Australia has over 30 Panicum spp. (panic grass) including several non-native species that cause crop and pasture loss due to competition. To develop appropriate management strategies for each species, it is critical to correctly identify panic grass species encountered. Currently, panic grass identification relies on microscopic examination of the inflorescence and spikelets, an approach that is only useful for flowering specimens and requires significant taxonomic expertise. To overcome this limitation, we applied both morphological and molecular techniques for identification of Panicum spp. in the Riverina region of New South Wales. We identified three molecular markers: one nuclear gene region (ITS) and two chloroplast gene regions (matK and trnL intron-trnF) capable of differentiating eight Panicum spp. Concatenation of sequences from ITS, matK and trnL intron-trnF gene regions provided clear separation of eight species collected regionally and identified a maximum intraspecific distance of 0.22% and minimum interspecific distance of 0.33%. Based on comparison with verified voucher specimens, P. hillmanii Chase was prevalent and constituted 78.9% of all samples collected and identified. DNA barcoding represents an accurate and potentially cost effective tool for distinguishing Panicum spp. at the species level regardless of growth stage. Molecular markers may also be useful for accurate demographic analysis of Panicum grass invasion in Australia and abroad. http://caws.org.nz/old-site/awc_contents.php?yr=2018#v_p125