High correlation of chemical composition with genotype in cryptic species of the liverwort Aneura pinguis

Abstract

Chemical constituents of cryptic species detected within the liverwort Aneura pinguis were identified using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Fibre coating with divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) was used. A total of 48 samples of A. pinguis were analysed. The studied plants were identified genetically based on barcode DNA sequences and represented three cryptic species (A, B and F) of A. pinguis. Cryptic species A and B are genetically diverse; both represent three evolutionary lineages: A1, A2, A3 and B1, B2, B3, respectively. The cryptic species F that was recently detected is not diverse. The most characteristic compounds in analysed samples were sesquiterpene hydrocarbons (up to 17.7% for A1; 15.7% for A2; 20.6% for A3; 7.7% for B1; 2.0% for B2; 3.7% for B3; 10.2% for F), oxygenated sesquiterpenoids (up to 68.0% for A1; 54.7% for A2; 52.6% for A3; 63.5% for B1; 88.7% for B2; 82.7% for B3; 78.8% for F), and linear aliphatic hydrocarbons (up to 14.8% for A1; 1.1% for A2; 12.1% for A3; 6.9 for B1; 5.2% for B2; 1.1% for B3; 7.0% for F). The dominant compound in the studied samples was pinguisone. The second dominant compound present in the tested plant material was deoxopinguisone, except for lineage B2, where only a small relative concentration of this compound was found. A high content of deoxopinguisone in cryptic species A (lineages A1, A2 and A3) was accompanied by the presence of isopinguisone and methyl norpinguisonate, whereas these two compounds were not detected in cryptic species B (lineages B1 and B3) and F. The chemical compounds detected in the studied samples of A. pinguis were subjected to multivariate statistical analysis. The results showed that the chemical composition depends mainly on the genotype of the plant and slightly on the habitat. However, there was no clear correlation between the volatile compounds and the date of collection of the studied plants.

Keywords: Aneura pinguis (L.) Dumort.; Aneuraceae; DNA sequences; Evolutionary lineages; GC-MS; HS-SPME; Liverworts; Multivariate statistical analyses; Terpenoids.