Chemical Fingerprinting of Cryptic Species and Genetic Lineages of Aneura pinguis (L.) Dumort. (Marchantiophyta, Metzgeriidae)

Seasonal Variability of Volatile Components in Calypogeia integristipula

Liverworts contain a large number of biologically active compounds that are synthesised and stored in their oil bodies. However, knowledge about the chemical composition of individual species is still incomplete. The subject of the study was Calypogeia integristipula, a species representing leafy liverworts. Plant material for chemotaxonomic studies was collected from various locations in Poland. The chemical composition was determined in 74 samples collected from the natural environment in 2021 and 2022 in three growing seasons: spring, summer and autumn, and for comparison with samples originating from in vitro culture. The plants were classified as Calypogeia integristipula on the basis of morphological characteristics, oil bodies, and DNA markers. The volatile organic compounds (VOCs) from the biological material were extracted by headspace solid phase microextraction (HS-SPME). The samples were then analysed by gas chromatography-mass spectrometry (GC-MS). A total of 79 compounds were detected, of which 44 compounds were identified. The remaining compounds were described using the MS fragmentation spectrum. Cyclical changes in the composition of compounds associated with the growing season of Calypogeia integristipula were observed. Moreover, samples from in vitro culture and samples taken from the natural environment were shown to differ in the composition of chemical compounds. In terms of quantity, among the volatile compounds, compounds belonging to the sesquiterpene group (46.54-71.19%) and sesqiuterpenoid (8.12-22.11%) dominate. A smaller number of compounds belong to aromatic compounds (2.30-10.96%), monoterpenes (0.01-0.07%), monoterpenoids (0.02-0.33%), and aliphatic hydrocarbons (1.11-6.12%). The dominant compounds in the analysed liverworts were: anastreptene (15.27-31.14%); bicyclogermacrene (6.99-18.09%), 4,5,9,10-dehydro-isolongifolene (2.00-8.72%), palustrol (4.95-9.94%), spathulenol (0.44-5.11%).

Integrative approaches to a revision of the liverwort in genus Aneura (Aneuraceae, Marchantiophyta) from Thailand

Background

The genus Aneura Dumort. is a simple thalloid liverwort with cosmopolitan distributions. Species circumscription is problematic in this genus due to a limited number of morphological traits. Two species are currently reported from Thailand, including A. maxima and A. pinguis. At the global scale, A. pinguis is considered a cryptic species, as the species contains several distinct genetic groups without clear morphological differentiation. At the same time, the identity of A. maxima remains unclear. In this work, we examined the level of diversity of Aneura species found in Thailand using both morphological and molecular data.

Methods

We measured the morphological traits and generated the molecular data (four markers: trnL-F, trnH-psbA, rbcL, and ITS2) from the Thai specimens. The concatenated dataset was then used to reconstruct phylogeny. Species delimitation with GMYC, bPTP, ASAP, and ABGD methods was performed to estimate the number of putative species within the genus.

Results

The samples of A. pinguis formed several clades, while A. maxima sequences from Poland were grouped in their clade and nested within another A. pinguis clade. We could not recover a sample of A. maxima from Thailand, even from the reported locality. Two putative species were detected among Thai Aneura samples. However, no morphological trait could distinguish the specimens from the two observed genetic groups.

Discussion

The previously observed paraphyletic nature of A. pinguis globally was also found among Thai samples, including several putative species. However, we could not confirm the identity of A. maxima from Thai specimens. The previous report could result from misidentification and problematic species circumscription within Aneura. The results highlighted the need to include multiple lines of evidence for the future taxonomic investigation of the group.

Comparison of Extraction Techniques for the Determination of Volatile Organic Compounds in Liverwort Samples

This article focuses on the comparison of four popular techniques for the extraction of volatile organic compounds (VOCs) from liverworts of the Calypogeia azurea species. Since extraction is the most important step in the sample analysis of ingredients present in botanical preparations, their strengths, and weaknesses are discussed. In order to determine the VOCs present in plants, selecting the appropriate one is a key step of the extraction technique. Extraction should ensure the isolation of all components present in the oily bodies of Calypogeia azurea without the formation of any artifacts during treatment. The best extraction method should yield the determined compounds in detectable amounts. Hydrodistillation (HD), applying Deryng apparatus and solid-liquid extraction (SLE), microwave-assisted extraction (MAE), and headspace solid-phase microextraction (HS-SPME) were used for volatile extraction. The extracts obtained were analysed by gas chromatography coupled to mass spectrometry (GC-MS) to determine the compounds.

Seasonal Variability and Effect of Sample Storage on Volatile Components in Calypogeia azurea

A change in the composition of specialized metabolites is often observed in stressed plants. Phytochemicals play an important role in adapting plants to the environment, particularly overcoming stress conditions such as temperature, humidity, and light intensity. In this study, seasonal variations in the concentrations of volatile organic compounds (VOCs) were analysed in species of Calypogeia azurea. The article presents the effect of sample storage on volatile organic compounds present in Calypogeia liverwort cells and whether the collection habitats of the sample affect the content of phytochemicals. The VOCs of the species within the liverwort Calypogeia azurea were analysed by GC-MS. Compounds were isolated from plant material using the HS-SPME technique. The samples were collected over several years (2019–2021). Of the several dozen samples collected, 79 compounds were isolated, of which 47 were identified.