Morphology and genome size of Epipactis helleborine (L.) Crantz (Orchidaceae) growing in anthropogenic and natural habitats

Diversity of genome size, endopolyploidy and SCoT markers in 20 Trigonella (Fabaceae) species

The Trigonella species possess medicinal, nutraceutical and pharmaceutical properties due to the presence of many bioactive compounds. Its therapeutic effects are mostly valuable in medicine, cosmetics and the functional food industry. Correct genetic characterisation of plant material is needed to increase the potential of Trigonella species by breeding and conservation programs. The aim of this study was to develop a reliable marker system to support the morphological and phytochemical analysis in Trigonella taxonomic research, species identification and characterization as well as determination of the interspecific variation within this genus along with relationships between species. For this purpose, flow cytometry and SCoT molecular markers were combined. Flow cytometric analyses revealed that Trigonella species possess very small and small genomes. The range of genome sizes was from 1.10 to 5.76 pg/2C, with most species possessing very small genomes (< 2.8 pg/2C). In seeds of 14 species endopolyploid nuclei were detected. Flow cytometric analysis of genome size enabled quick identification of four out of 20 species, while combined with endopolyploidy detection in seeds, facilitated distinction of the next seven species. ScoT molecular markers helped to identify closely related species with similar genome size and cell cycle activity. Therefore, flow cytometry was proposed as the first-choice method for quick accession screening, while the more detailed genetic classification was obtained using SCoT molecular markers.

Epipactis bucegensis-A Separate Autogamous Species within the E. helleborine Alliance

A new species of Epipactis from Bucegi Natural Park ROSCI0013, Southern Carpathians, Central Romania is described. Three medium-sized populations of Epipactis bucegensis (65-70 individuals in total) were discovered in the south-eastern, subalpine area of the park. To properly describe and distinguish the newly found taxon from other Romanian Epipactis, 37 morphological characters were measured directly from living plants and flowers. Moreover, a detailed taxonomic treatment and description with corresponding colour photos and line drawings illustrations of the holotype are also included. Epipactis bucegensis is an obligate autogamous species that partially resembles Epipactis muelleri, from which it differs in the basal distribution of leaves on the stem (vs. median distribution); near-erect leaf posture (vs. horizontally spread, arched downwards); lanceolate-acuminate, yellowish-green leaves (vs. oval-elongate, vivid-green leaves); bipartite labellum lacking the mesochile (vs. tripartite labellum); crimson-red, wide, ovoid-elongated, flattened hypochile (vs. dark-brown to black roundish hypochile); triangular, white epichile with a sharply tapering apex (vs. heart-shaped, greenish-yellow epichile with obtuse, roundish apex); and two wide-apart, purple, pyramidal calli (vs. two closely placed, attenuated, mildly wrinkled, greenish-yellow calli). Epipactis bucegensis is easily distinguished from all other European Epipactis taxa by the bipartite, wide labellum that lacks the mesochile. In addition, information regarding its distribution (maps), habitat, ecology, phenology and IUCN conservation assessments are provided.

Does Reproductive Success in Natural and Anthropogenic Populations of Generalist Epipactis helleborine Depend on Flower Morphology and Nectar Composition?

The purpose of our study was to determine the role of flower structure and nectar composition in shaping the reproductive success (RS) of the generalist orchid Epipactis helleborine in natural and anthropogenic populations. We supposed that the distinct character of two groups of habitats creates different conditions for plant-pollinator relationships, thus influencing reproductive success in E. helleborine populations. Both pollinaria removal (PR) and fruiting (FRS) were differentiated between the populations. On average, FRS was almost two times higher in the anthropogenic than in the natural populations. The difference between the two population groups in PR was smaller but still statistically significant. RS parameters were correlated with some floral display and flower traits. Floral display influenced RS only in three anthropogenic populations. Flower traits had a weak influence on RS (10 of the 192 cases analyzed). The more important trait in shaping RS was nectar chemistry. The nectar of E. helleborine is relatively diluted with a lower sugar concentration in the anthropogenic than in the natural populations. In the natural populations, domination of sucrose over hexoses was found, while in the anthropogenic populations, hexoses were more abundant and the participation of sugars was balanced. In some populations, sugars influenced RS. In E. helleborine nectar, 20 proteogenic and 7 non-proteogenic amino acids (AAs) were found with a clear domination of glutamic acid. We noted relationships between some AAs and RS, but distinct AAs shaped RS in different populations, and their impact was independent of their participation. Our results indicate that the flower structure and nectar composition of E. helleborine reflect its generalistic character and meet the requirements of a wide range of pollinators. Simultaneously, the differentiation of flower traits suggests a variation in pollinator assemblages in particular populations. Knowledge about the factors influencing RS in distinct habitats helps to understand the evolutionary potential of species and to understand mechanisms and processes crucial for shaping interactions between plants and pollinators.

Chromosome Number and Genome Size Evolution in Brasolia and Sobralia (Sobralieae, Orchidaceae)

Despite the clear circumscription of tribe Sobralieae (Orchidaceae), its internal relationships are still dubious. The recently delimited genus Brasolia, based on previous Sobralia species, is now assumed to be paraphyletic, with a third genus, Elleanthus, nested in it. The morphology of these three genera is significantly different, indicating the necessity of new data for a better genera delimitation. Though morphology and molecular data are available, cytogenetics data for Sobralieae is restricted to two Sobralia and one Elleanthus species. Aiming to evaluate the potential of cytogenetic data for Brasolia-Elleanthus-Sobralia genera delimitation, we present chromosome number and genome size data for 21 and 20 species, respectively, and used such data to infer the pattern of karyotype evolution in these genera. The analysis allowed us to infer x = 24 as the base chromosome number and genome size of average 1C-value of 5.0 pg for the common ancestor of Brasolia-Elleanthus-Sobralia. The recurrent descending dysploidy in Sobralieae and the punctual genome upsize suggest a recent diversification in Sobralieae but did not allow differing between Brasolia and Sobralia. However, the basal position of tribe Sobralieae in the subfamily Epidendroideae makes this tribe of interest to further studies clarifying the internal delimitation and pattern of karyotype evolution.

The Epipactis helleborine Group (Orchidaceae): An Overview of Recent Taxonomic Changes, with an Updated List of Currently Accepted Taxa

The Epipactis helleborine (L.) Crantz group is one of the most taxonomically challenging species complexes within the genus Epipactis. Because of the exceptionally high levels of morphological variability and the ability to readily cross with other species, ninety different taxa at various taxonomic ranks have already been described within its nominative subspecies, but the taxonomic status of most of them is uncertain, widely disputed, and sometimes even irrelevant. The present review is based on results of the most recent research devoted to the E. helleborine group taxonomy. In addition, we analysed data about taxa belonging to this group presented in some research articles and monographs devoted directly to the genus Epipactis or to orchids in certain area(s). Based on the reviewed literature and data collected in four taxonomic databases available online, we propose an updated list of the 10 currently accepted taxa in the E. helleborine group (two species, six subspecies, and two varieties), which includes E. helleborine (L.) Crantz subsp. helleborine; E. helleborine subsp. bithynica (Robatsch) Kreutz; E. helleborine subsp. distans (Arv.-Touv.) R.Engel and P.Quentin; E. helleborine subsp. neerlandica (Verm.) Buttler; E. helleborine var. tangutica (Schltr.) S.C.Chen and G.H.Zhu; E. helleborine subsp. tremolsii (Pau) E.Klein; E. helleborine subsp. voethii (Robatsch) Jakubska-Busse, Żołubak, and Łobas, stat. nov.; E. condensata Boiss. ex D.P.Young; E. condensata var. kuenkeleana (Akhalk., H.Baumann, R.Lorenz, and Mosul.) Popovich; and E. cupaniana C.Brullo, D’Emerico, and Pulv.

Genome Size Diversity in Rare, Endangered, and Protected Orchids in Poland

Orchidaceae is one of the largest and the most widespread plant families with many species threatened with extinction. However, only about 1.5% of orchids’ genome sizes have been known so far. The aim of this study was to estimate the genome size of 15 species and one infraspecific taxon of endangered and protected orchids growing wild in Poland to assess their variability and develop additional criterion useful in orchid species identification and characterization. Flow cytometric genome size estimation revealed that investigated orchid species possessed intermediate, large, and very large genomes. The smallest 2C DNA content possessed Liparis loeselii (14.15 pg), while the largest Cypripedium calceolus (82.10 pg). It was confirmed that the genome size is characteristic to the subfamily. Additionally, for four species Epipactis albensis, Ophrys insectifera, Orchis mascula, Orchis militaris and one infraspecific taxon, Epipactis purpurata f. chlorophylla the 2C DNA content has been estimated for the first time. Genome size estimation by flow cytometry proved to be a useful auxiliary method for quick orchid species identification and characterization.

Iterative allogamy-autogamy transitions drive actual and incipient speciation during the ongoing evolutionary radiation within the orchid genus Epipactis (Orchidaceae)

BACKGROUND AND AIMS

The terrestrial orchid genus Epipactis has become a model system for the study of speciation via transitions from allogamy to autogamy, but close phylogenetic relationships have proven difficult to resolve through Sanger sequencing.

METHODS

We analysed with restriction site-associated sequencing (RAD-seq) 108 plants representing 29 named taxa that together span the genus, focusing on section Epipactis. Our filtered matrix of 12 543 single nucleotide polymorphisms was used to generate an unrooted network and a rooted, well-supported likelihood tree. We further inferred genetic structure through a co-ancestry heat map and admixture analysis, and estimated inbreeding coefficients per sample.

KEY RESULTS

The 27 named taxa of the ingroup were resolved as 11 genuine, geographically widespread species: four dominantly allogamous and seven dominantly autogamous. A single comparatively allogamous species, E. helleborine, is the direct ancestor of most of the remaining species, though one of the derived autogams has generated one further autogamous species. An assessment of shared ancestry suggested only sporadic hybridization between the re-circumscribed species. Taxa with the greatest inclination towards autogamy show less, if any, admixture, whereas the gene pools of more allogamous species contain a mixture alleles found in the autogams.

CONCLUSIONS

This clade is presently undergoing an evolutionary radiation driven by a wide spectrum of genotypic, phenotypic and environmental factors. Epipactis helleborine has also frequently generated many local variants showing inclinations toward autogamy (and occasionally cleistogamy), best viewed as incipient speciation from within the genetic background provided by E. helleborine, which thus becomes an example of a convincingly paraphyletic species. Autogams are often as widespread and ecologically successful as allogams.