Secondary chemistry and ribosomal DNA data congruencies in Arnica (Asteraceae)

Abstract

To investigate possible congruencies between DNA sequence data and secondary chemistry, we compared nuclear ribosomal DNA (nrDNA) sequence data, sesquiterpene lactone (STL) contents, and cytometric data from 35 accessions of 16 Arnica (Asteraceae) species and two outgroup taxa (Layia hieracioides and Madia sativa), using phylogenetic inference and principal component analysis (PCA). Several groups supporting multiple accessions of the same species (of A. montana, A. longifolia, A. gracilis, and A. chamissonis) are congruent between the phylogenetic trees based on nrDNA and STL data. Sesquiterpene lactone profiles were found to be highly consistent within multiple samples of A. montana and A. longifolia respectively. Moreover, sesquiterpene lactone data support subspecies classifications of A. chamissonis and A. parryi, with additional support from DNA sequence data and cytometric data. Morphology, STL data (PCA), cytometric data and DNA sequence data suggest a hybrid origin of one accession (A. gracilis · longifolia). In A. gracilis, A. latifolia, and Layia hieracioides, previously not investigated for STLs, we found large amounts of xanthalongin derivatives. This is the first time STLs have been reported from subtribe Madiinae.

Phylogeography and genetic variability of the Arnica montana chemotypes in NW Iberian Peninsula

“…Although the taxonomic status of the A. montana subspecies is doubtful in the study area (ROMERO et al, 2011), the morphological and chemotypical variability described above suggests the possible existence of genetic differences among arnica populations in this area. Genetic studies on this species are scarce (KAHMEN and POSCHLOD, 2000;LUIJTEN et al, 2000;EKENÄS et al, 2007EKENÄS et al, , 2009 despite the economical and conservation interests of the species. Therefore the main objective of this study was to investigate for the first time the phylogeography and genetic variation associated with the two previously described chemotypes for A. montana in order to consider this information for the conservation strategy of the species in Galicia and provide more effective management plans.…”

Discovery of germacrene A synthases in Barnadesia spinosa: The first committed step in sesquiterpene lactone biosynthesis in the basal member of the Asteraceae

“…Further, GAO activities are highly conserved throughout the Asteraceae, even at the evolutionary base; an observation that implies the presence of enzymatic machinery for the first oxidative transformation of germacrene A predates geographical expansion of the Asteraceae family. Given the clear congruencies of STL specialized metabolism and DNA sequence in the Asteraceae [25], the physical juxtaposition of GAS and GAO by genomic rearrangement was a likely scenario leading to synchronized expression and ultimately STL biosynthesis, consistent with the co-occurrence of TPS/P450 sets in sequenced plant genomes [26]. As a unit, the GAS/GAO tandem produces GAA leading to the simplest germacranolide (e.g.…”

Genetic structure of colline and montane populations of an endangered plant species

“…The leaf samples were immediately stored in silica gel and kept at room temperature until DNA extraction. In several populations, we had problems with the PCR-reaction, probably due to the high content of secondary metabolites in the leaf tissue of A. montana ( Ekenäs et al 2009 ) and a lower number of samples were used for the genetic analyses ( Table 1 ).…”