Molecular diagnostics of Lemon Myrtle (Backhousia citriodora versus Leptospermum citratum)


‘Lemon Myrtle’ is becoming increasingly popular in Europe both for use in cuisine and phytotherapy. However, this common name covers two completely different species, Backhousia citriodora F. Muell. and Leptospermum citratum Challinor, Cheel & A.R.Penfold. These species differ with respect to secondary compounds and even can cause, if mixed up and applied in high dose, toxic effects. We describe how the two species can be discriminated microscopically making use of differences in the morphology of leaf pavement cells and the relative size of palisade parenchyma. Based on the large subunit of ribulose-1,5-bisphosphate carboxylase oxygenase (rbcL) as molecular marker, the phylogenetic position of the two species within the Myrtaceae could be clarified. This sequence information was used to develop a simple assay to discriminate the two species even in dried and highly fragmented mixtures as typically occurring in commercial samples. This assay utilises the occurrence of single-nucleotide exchanges between those species that produce different fragments when the rbcL amplificates are restricted with Sac II.

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We acknowledge Angelika Piernitzki and Joachim Daumann, Botanical Garden of the University, for excellent horticultural support during the project and Olivia Huber for skillful technical support during DNA extraction and analysis.

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The authors declare that they do not have any conflict of interest.

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Correspondence to Peter Nick.

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Horn, T., Barth, A., Rühle, M. et al. Molecular diagnostics of Lemon Myrtle (Backhousia citriodora versus Leptospermum citratum). Eur Food Res Technol 234, 853–861 (2012).

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  • Backhousia citriodora F.Muell
  • Lemon Myrtle
  • Leptospermum citratum Challinor, Cheel & A.R.Penfold
  • Molecular identification
  • Polymerase chain reaction (PCR)
  • Ribulose-bisphosphate carboxylase oxygenase large subunit (rbcL)