title: Metabolic Profiling and Identification of Shikonins in Root Periderm of Two Invasive Echium spp. Weeds in Australia.
abstract: Metabolic profiling can be successfully implemented to analyse a living system's response to environmental conditions by providing critical information on an organism's physiological state at a particular point in time and allowing for both quantitative and qualitative assessment of a specific subset(s) of key metabolites. Shikonins are highly reactive chemicals that affect various cell signalling pathways and possess antifungal, antibacterial and allelopathic activity. Based on previous bioassay results, bioactive shikonins, are likely to play important roles in the regulation of rhizosphere interactions with neighbouring plants, microbes and herbivores. An effective platform allowing for rapid identification and accurate profiling of numerous structurally similar, difficult-to-separate bioactive isohexenylnaphthazarins (shikonins) was developed using UHPLC Q-TOF MS. Root periderm tissues of the invasive Australian weedsEchium plantagineumand its congenerE. vulgarewere extracted overnight in ethanol for shikonin profiling. Shikonin production was evaluated at seedling, rosette and flowering stages. Five populations of each species were compared for qualitative and quantitative differences in shikonin formation. Each species showed little populational variation in qualitative shikonin production; however, shikonin was considerably low in one population ofE. plantagineumfrom Western New South Wales.Seedlings of all populations produced the bioactive metabolite acetylshikonin and production was upregulated over time. Mature plants of both species produced significantly higher total levels of shikonins and isovalerylshikonin > dimethylacrylshikonin > shikonin > acetylshikonin in matureE. plantagineum. Although qualitative metabolic profiles in bothEchiumspp. were nearly identical, shikonin abundance in mature plant periderm was approximately 2.5 times higher in perennialE. vulgareextracts in comparison to those of the annualE. plantagineum.These findings contribute to our understanding of the biosynthesis of shikonins in roots of two related invasive plants and their expression in relation to plant phenological stage.
authors.affiliation: Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2678, Australia. dskoneczny@csu.edu.au.
authors.forename: Dominik
authors.initials: D
authors.lastname: Skoneczny
authors.affiliation: Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2678, Australia. pweston@csu.edu.au.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Weston
authors.affiliation: Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2678, Australia. xzhu@csu.edu.au.
authors.forename: Xiaocheng
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2678, Australia. ggurr@csu.edu.au.|Institute of Applied Ecology, Fujian Agriculture & Forestry University, Fuzhou 350002, China. ggurr@csu.edu.au.
authors.forename: Geoff M
authors.initials: GM
authors.lastname: Gurr
authors.affiliation: Division of Biological Science, University of Montana, 32 Campus Dr, Missoula, MT 59812, USA. ray.callaway@mso.umt.edu.
authors.forename: Ragan M
authors.initials: RM
authors.lastname: Callaway
authors.affiliation: Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia. rab@anu.edu.au.
authors.forename: Russel A
authors.initials: RA
authors.lastname: Barrow
authors.affiliation: Graham Centre for Agricultural Innovation, Charles Sturt University, Wagga Wagga, NSW 2678, Australia. leweston@csu.edu.au.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Weston
mesh_terms: D001315:Australia; D002851:Chromatography, High Pressure Liquid; D036661:Echium / Q000737:chemistry*; D055442:Metabolome; D055432:Metabolomics / Q000379:methods; D015394:Molecular Structure; D009285:Naphthoquinones / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry*; D057685:Plant Weeds / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D009285:Naphthoquinones; D010936:Plant Extracts; C016101:shikonin
keywords: UHPLC MS Q-TOF; metabolomics; naphthoquinones; plant defence; rhizosphere; secondary plant products