Bamboo tea: reduction of taxonomic complexity and application of DNA diagnostics based onrbcLandmatKsequence data

Abstract

BackgroundNames used in ingredient lists of food products are trivial and in their nature rarely precise. The most recent scientific interpretation of the term bamboo (Bambusoideae,Poaceae) comprises over 1,600 distinct species. In the European Union only few of these exotic species are well known sources for food ingredients (i.e., bamboo sprouts) and are thus not considered novel foods, which would require safety assessments before marketing of corresponding products. In contrast, the use of bamboo leaves and their taxonomic origin is mostly unclear. However, products containing bamboo leaves are currently marketed.MethodsWe analysed bamboo species and tea products containing bamboo leaves using anatomical leaf characters and DNA sequence data. To reduce taxonomic complexity associated with the term bamboo, we used a phylogenetic framework to trace the origin of DNA from commercially available bamboo leaves within the bambusoid subfamily. For authentication purposes, we introduced a simple PCR based test distinguishing genuine bamboo from other leaf components and assessed the diagnostic potential ofrbcLandmatKto resolve taxonomic entities within the bamboo subfamily and tribes.ResultsBased on anatomical and DNA data we were able to trace the taxonomic origin of bamboo leaves used in products to the generaPhyllostachysandPseudosasafrom the temperate “woody” bamboo tribe (Arundinarieae). Currently availablerbcLandmatKsequence data allow the character based diagnosis of 80% of represented bamboo genera. We detected adulteration by carnation in four of eight tea products and, after adapting our objectives, could trace the taxonomic origin of the adulterant toDianthus chinensis(Caryophyllaceae), a well known traditional Chinese medicine with counter indications for pregnant women.