Search Results (58)

Himantoglossum metlesicsianum is a threatened orchid with low population numbers and fragmented distribution, present in four of the Canary Islands. This study focused on assessing the genetic variability and population genetic structure of the natural populations known to date, identifying those characteristics of the species that condition the flow and genetic variation. For that purpose, we collected samples from eight sites in its distribution range and developed 14 polymorphic microsatellite markers. Despite its rarity, this orchid presents high levels of genetic diversity and a homogeneous population structure, characterised by a low degree of genetic differentiation and patterns consistent with high genetic connectivity among populations. Our results suggest that the species might show dichotomy in seed dispersal, combining long- and short-distance events. In addition, it is possible that pollen cross-pollination (pollinia) between adjacent sites may also be involved. In conclusion, these findings reveal unexpectedly high genetic diversity and connectivity among populations, despite the species’ rarity and fragmented distribution, highlighting key biological traits that should be considered in future conservation and recovery plans. Full article

This study investigated dynamic pollen–stigma coordination to optimize interspecific hybridization in Dendrobium using D. ‘Burana Jade’ as the maternal parent and eight wild species as pollen donors. Stigma receptivity was comprehensively evaluated using a multi-indicator approach, including morphological characterization (crystal secretion and bulging papillae), histochemical benzidine-H₂O₂ staining, and enzymatic activity profiling (esterase and superoxide dismutase). Concurrently, pollen viability was assessed through TTC testing coupled with ultrastructural observations. Results identified a critical synchronization window: pollen viability peaked at 1–3 days post anthesis (DPA) or during the mid-anthesis phase, while stigmas exhibited maximal receptivity when secretory activity and antioxidant enzyme levels significantly increased. Using stage-specific pollination criteria, 8.4% of crosses (8/95) produced viable fruits, outperforming empirical methods by 2.8-fold. D. ‘Burana Jade’ showed cross-compatibility with four Dendrobium species (D. aphyllum, D. chrysotoxum, D. hercoglossum, D. thyrsiflorum), with D. thyrsiflorum hybrids achieving 54.81% embryogenesis and 22.38% germination. Three compatible combinations germinated successfully in vitro within 45–55 days on 1/4 MS medium supplemented with 20 g/L sucrose, 1 g/L tryptone, 180 mL/L coconut water, and 2.2 g/L Phytagel. Our findings establish that synchronizing pollen viability windows with stigma receptivity phases significantly enhances fruit set and hybrid seed viability, providing a phenology-driven strategy to overcome reproductive barriers in orchid breeding programs. This study provides key physiological criteria for Dendrobium hybridization, though their applicability to other orchids needs validation. Future multi-omics studies should explore cross-species compatibility mechanisms. Full article

Studies on the gain or loss of nectar during the course of evolution in Dendrobium Sw. (Orchidaceae) are able to provide important information concerning the reproductive biology of this enormous orchid genus and highlight reproductive barriers—in particular, changes to compatibility. By employing a literature search on the compatibility system of Dendrobium, supplemented by new experimental data of 13 taxa investigated by means of microscopy, histochemistry, and phylogenetic analysis, we aimed to ascertain whether there is, in this genus, a relationship between self-compatibility (SC) and the presence of nectar. Nectariferous plant species are thought to be visited more frequently by pollinators, resulting in geitonogamy or selfing; therefore, the presence of nectar in some Dendrobium species may promote self-incompatibility (SI), whereas a lack of nectar may increase cross-pollination. Our investigations confirmed that the capacity for nectar secretion was gained and lost several times in this genus, and that similarly organized nectar spurs were present in all species investigated, regardless of their ability to produce nectar. SI, SC, and the presence or absence of nectar have all evolved independently, but, of the 42 taxa investigated whose status both relating to nectar presence and compatibility was known, nectar was more frequent in self-incompatible taxa. Full article

Understanding the complexity of flower scent—a crucial attractant for pollinators and a key factor in ensuring plant reproduction—is an essential ecological task for highly endangered orchids. To address this issue, we studied the flower volatiles profile of Neottia ovata, a nectar-rewarding orchid known for its generalist pollination strategy. We then compared the chemical composition of N. ovata floral scent with scent data of other orchid species to place our findings in the context of general volatile attractants emitted by nectar-rewarding or food-deceptive species. Our results contribute to understanding the complexity of the N. ovata floral scent profile and provide valuable methodological insights. The scented bouquet of N. ovata comprises 100 compounds with a relatively consistent composition across the analyzed samples. It is rich in terpenes, including linalool and trans-/cis-sabinene hydrate, compounds commonly associated with generalized rewarding or food-deceptive pollination systems. Other terpenes identified include α- and β-pinene, limonene, and β-phellandrene, whose presence underscores the generalized nature of the floral scent. Interestingly, in the studied N. ovata populations, the dominance among terpenes is shifting markedly towards γ-terpinene, α-terpinene, and terpinene-4-ol, commonly found in essential oils and the floral scents of some supergeneralist-pollination plants. Aromatic compounds were less represented in the N. ovata scent profile and those of other orchids studied, though benzyl alcohol and benzaldehyde were noticeably more abundant. Aliphatic compounds composed the least prevalent fraction, showing a marked decreasing trend among nectar-rewarding species with generalized or specialized pollination systems. It is worth emphasizing that the applied methodology revealed an extensive group of low-frequency compounds in the N. ovata floral scent. This finding raises new ecological questions about the intraspecific diversity of floral scent profiles and sheds new light on the factors determining effective reproduction in this species of orchid. Full article

Background: Research on orchids has experienced substantial growth since the early 20th century, reflecting their ecological and evolutionary significance. Methods: This paper provides a comprehensive bibliometric analysis of orchid-related literature published between 1902 and 2024, based on data retrieved from the Web of Science Core Collection™ (WoS). Results: The primary goal is to assess the global research landscape of orchids by identifying key authors, institutions, and journals, as well as major research themes in the field. A thorough analysis of publication trends, citation frequencies, and keyword co-occurrence networks was conducted to uncover significant research hotspots. The findings indicate that orchid research has evolved from foundational topics such as taxonomy and classification to more intricate subjects, including conservation strategies, orchid-pollinator dynamics, and the role of orchids in ecosystem functions. Additionally, biotechnology-related research is emerging as a dominant trend. This study also highlights that China has the highest publication output, while collaboration between the United States and Europe continues to grow. The co-word analysis of keywords suggests that future research is likely to continue to focus on orchid conservation, the impacts of climate change, pollination biology, and symbiotic relationships with mycorrhizal fungi. Conclusions: This review offers valuable insights for researchers and conservationists, helping to identify future research priorities and strategies for the preservation and sustainable use of orchids. Full article

Specklinia digitale is an epiphytic orchid endemic to Mexico. The destruction of its habitat has resulted in it being regarded as an endangered species, and, to our knowledge, no effort has been made to establish ex situ conservation programs. Here, we describe an in situ assessment of flower and fruit phenology and subsequent in vitro germination. We also established a successful protocol for asymbiotic in vitro germination and acclimatization using Murashige–Skoog (MS) medium at full (full-MS) and half (1/2 MS) strength as well as activated charcoal (AC). All-year flower and fruit production was confirmed. Nevertheless, we observed a low pollination occurrence. No significant difference in germination rate was found for the four treatments tested; however, after protocorm evaluation, full-MS plus AC emerged as the best treatment for S. digitale in vitro propagation. Germination of up to 90.53% was achieved in full-MS. The acclimatization survival was 95%. These observations and our effective germination protocol can be used in a comprehensive approach for conservation efforts of this species. Full article

Orchids have evolved flowers with unique morphologies through coevolution with pollinators, such as insects. Among the floral organs, the lip (labellum), one of the three petals, exhibits a distinctive shape and plays a crucial role in attracting pollinators and facilitating pollination in many orchids. The lip of the terrestrial orchid Habenaria radiata is shaped like a flying white bird and is believed to attract and provide a platform for nectar-feeding pollinators, such as hawk moths. To elucidate the mechanism of lip morphogenesis, we conducted time-lapse imaging of blooming flowers to observe the extension process of the lip and analyzed the cellular morphology during the generation of serrations. We found that the wing part of the lip folds inward in the bud and fully expands in two hours after blooming. The serrations of the lip were initially formed through cell division and later deepened through polar cell elongation. Transcriptome analysis of floral buds revealed the expression of genes involved in floral organ development, cell division, and meiosis. Additionally, genes involved in serration formation are also expressed in floral buds. This study provides insights into the mechanism underlying the formation of the unique lip morphology in Habenaria radiata. Full article

Background: The patterns of inbreeding coefficients (F_IS) and fine spatial genetic structure (FSGS) were evaluated regarding the mating system and inbreeding depression of food-deceptive orchids, Dactylorhiza majalis, Dactylorhiza incarnata var. incarnata, and Dactylorhiza fuchsii, from NE Poland. Methods: We used 455 individuals, representing nine populations of three taxa and AFLPs, to estimate percent polymorphic loci and Nei’s gene diversity, which are calculated using the Bayesian method; F_IS; F_ST; FSGS with the pairwise kinship coefficient (Fij); and AMOVA in populations. Results: We detected a relatively high proportion of polymorphic fragments (40.4–68.4%) and Nei’s gene diversity indices (0.140–0.234). The overall F_IS was relatively low to moderate (0.071–0.312). The average Fij for the populations of three Dactylorhiza showed significantly positive values, which were observed between plants at distances of 1–10 m (20 m). F_ST was significant in each Dactylorhiza taxon, ranging from the lowest values in D. fuchsii and D. majalis (0.080–0.086, p < 0.05) to a higher value (0.163, p < 0.05) in D. incarnata var. incarnata. Molecular variance was the highest within populations (76.5–86.6%; p < 0.001). Conclusions: We observed concordant genetic diversity patterns in three food-deceptive, allogamous, pollinator-dependent, and self-compatible Dactylorhiza. F_IS is often substantially higher than Fij with respect to the first class of FSGSs, suggesting that selfing (meaning of geitonogamy) is at least responsible for homozygosity. A strong FSGS may have evolutionary consequences in Dactylorhiza, and combined with low inbreeding depression, it may impact the establishment of inbred lines of D. majalis and D. incarnata var. incarnata. Full article

The natural fertilization of Vanilla planifolia has long been a matter of speculation. Stingless (tribe Meliponini) and orchid bees (tribe Euglossini) are often cited as effective pollinators, but direct evidence is notoriously lacking. As with other food-deceptive orchids, the natural fruit-set in V. planifolia is low and does not occur spontaneously outside its native range in Middle America. Fruiting has, therefore, necessitated human intervention through artificial pollination. How Vanilla first came to be artificially pollinated is a controversial issue spurring egotism and nationalism. There are numerous texts offering differing versions of the historical events that led to the discovery of the artificial fertilization of V. planifolia and its propagation as a crop. Historical records show Vanilla was simultaneously being pollinated in several parts of the world. I argue that the suspected independent simultaneous discoveries made in Liège, Paris, Padua, the Dutch colony of Java (Indonesia), and the French insular colonies Réunion (Bourbon), Guadeloupe, and Martinique are not unconnected. I conclude that they can be traced back to a single discoverer whose feat was spread around the globe by a tight network of corresponding naturalists. This view contrasts with previous authors. Finally, current concerns regarding Vanilla pollination and production are addressed, highlighting the need for immediate actions to conserve the genetic diversity of the crop’s wild relatives to attenuate the effect of extreme climates in a changing world. A plea is made to shift the focus to Middle America, stimulating and supporting local research and conservation efforts and the allocation of funds from this billion-dollar industry. Full article

Danxiaorchis yangii, a newly discovered fully mycoheterotrophic orchid. It relies on Lysimachia alfredii and Dufourea spp. for pollination, and environmental factors closely influence the growth and distribution of these pollinators, which in turn directly affects the growth and reproduction of D. yangii. Climate change threatens the suitable habitats for these three species, emphasizing the need to understand D. yangii’s response. This study comprehensively utilized the field distribution of D. yangii and related climatic data, along with future climate predictions from global models, to predict the climate suitability areas of D. yangii under two greenhouse gas emission scenarios (SSP245 and SSP370) using species distribution models (SDMs), which encompassed a random forest (RF) model. Additionally, we selected the optimal ensemble model (OEM) for Dufourea spp. and applied generalized boosted models (GBMs) and RF for L. alfredii in our predictions. The study found that precipitation of the driest quarter plays a pivotal role in determining the distribution of D. yangii, with an optimal range of 159 to 730 mm being most conducive to its growth. Comparative analysis further indicated that precipitation exerts a greater influence on D. yangii than temperature. Historically, D. yangii has been predominantly distributed across Jiangxi, Hunan, Zhejiang, and the Guangxi Zhuang Autonomous Region, with Jiangxi Province containing the largest area of highly suitable habitat, and this distribution largely overlaps with the suitable regions of its pollinators. Full article

The pollination characteristics and flowering phenology of Calanthe sieboldii were evaluated to elucidate its reproductive characteristics and breeding systems. Field observations and artificial pollination experiments were conducted to study the pollination biology in Xuancheng City, Anhui Province. Meanwhile, gas chromatography–mass spectrometry (GC-MS) was employed to analyze the species’ volatile organic compounds (VOCs). Key findings include the following: (1) the flowering period extends from mid-April to mid-May, with a population-level flowering duration of 29 days in 2017, individual plant flowering averaging 20.22 days, and single flower longevity ranging from 12 to 23 days (mean = 19.30 days); (2) the species exhibits deceptive nectar guides devoid of nectar, indicating food-deceptive pollination, with Bombus sp. identified as its primary pollinator; (3) the pollinial–ovule ratio and hybridization index suggest a high level of self-compatibility without autonomous self-pollination, with no significant difference in pollination success between self- and outcross populations; (4) GC-MS analysis identified methyl benzoate and acacia-related compounds as the primary VOCs of C. sieboldii. These findings provide valuable insights into the conservation and sustainable management of orchids, particularly C. sieboldii. Full article

Orchid flowers have evolved in concert with pollinators to form highly specialized structures resulting in zygomorphy. In dicotyledons, it is widely accepted that CYC-like genes are involved in the dorsoventral polarity establishment of flowers, which determines the development of zygomorphic flowers. However, the function of TCP transcription factors involved in orchid floral development is rarely known. Here, we found 15 unigenes with TCP domain (EpTCPs) from the previously reported Erycina pusilla unigene database. The expression patterns of EpTCPs in various tissues and different floral organs were successively detected by quantitative real-time PCR. The results revealed that the CYC-like gene (EpTCP25) and CIN-like genes (EpTCP11 and EpTCP26) were highly expressed in inflorescences but lowly expressed in leaves and roots. What is more, these three genes were expressed relatively high in the dorsal labellum, and EpTCP26 showed differential expression along the dorsoventral polarity of tepals, which was high in the dorsal and low in the ventral. Ectopic expression of EpTCP25 in Arabidopsis repressed primary root growth and delayed flowering. EpTCP26 overexpression in Arabidopsis promoted primary root growth and leaf growth. In contrast, EpTCP11 overexpression repressed primary root growth and changed the radially symmetric flower to a bilaterally symmetric flower by inhibiting the elongation of one or two adjacent petals. In addition, the homeotic transition of floral organs is generated when these genes are ectopically expressed in Arabidopsis, suggesting their roles in floral morphogenesis. Altogether, our results indicate that CIN-like genes would be associated with the unique flower pattern development of Erycina pusilla. Full article

Pollination by sexual deception specifically attracts male insects, through the floral scent and particular morphological features of the flower that serve as visual and tactile stimuli. The unique bond between the Ophrys speculum orchid and the male Dasyscolia ciliata wasp primarily stems from a few distinctive semiochemicals that mimic the female wasp’s sex pheromone, although the floral scent comprises a variety of compounds. An osmophore producing highly volatile compounds has been documented in four close relatives of O. speculum and is now being also investigated in this species. Given the existing debates regarding the structure of the labellum and stigmatic cavity in O. speculum, this study details their micromorphology. Additionally, comparisons of O. speculum flowers and female D. ciliata wasps under stereomicroscopy and scanning electron microscopy are conducted to seek new evidence of visual and tactile mimicry. The findings confirm that (i) an osmophore is present at the apical margin of the labellum in O. speculum flowers; (ii) the labellum features a distinct basal field homologous to those found in other Ophrys species; and (iii) the basal labellum region closely mimics the female wasp’s thorax and wings. The implications of these novel floral features are discussed within an evolutionary context. Full article

A novel species, Gymnadenia winkeliana, has been identified in the Bucegi Natural Park ROSCI0013, located in the Southern Carpathians of Central Romania. Two moderately sized populations of Gymnadenia winkeliana, totalling 120–140 individuals, were discovered inhabiting the alpine grasslands of the park, situated 2.000 m above sea level. To describe this newly found population as comprehensively as possible, 44 vegetative and floral organs/organ parts were directly studied and measured from living plants. Special attention was focused on the characteristics that proved to have taxonomic significance, particularly those involving distinctive details in the morphology of the leaves, perianth, labellum and gynostemium. A total of 223 characteristics were analysed encompassing the morphology of every organ of the plant, cytology and breeding system. Furthermore, comprehensive taxonomic treatment and description, accompanied by colour photographs illustrating the holotype, are provided. Voucher specimens were deposited at the Herbarium of the University of Agriculture and Veterinary Medicine, Bucharest (USAMVB Herbarium barcode: 40102, NEA); Gymnadenia winkeliana, a (micro)endemic species, is characterized as a putative allogamous, facultatively apomict that significantly differs from other Gymnadenia R.Br. species found in Romania. Notably, it distinguishes itself through its smaller habitus (reaching heights of up to 8–10 cm), its two-coloured, rounded/hemispherical inflorescence displaying a gradient of pink hues in an acropetal fashion (ranging from whitish-pink at the base to vivid-pink at the topmost flowers), and its limited distribution in high-altitude areas, encompassing approximately 8–10 km² in the central area of the Bucegi Natural Park. This species has been under observation since 2005, with observed population numbers showing a significant increase over time, from ca. 50–55 (counted at the time of its discovery) to 120–140 individuals (counted in June 2023). Additionally, comprehensive information regarding the habitat, ecology, phenology and IUCN conservation assessments of Gymnadenia winkeliana are provided, including maps illustrating its distribution. Full article

Orchids are among the plants most threatened by anthropic impact and environmental changes. Therefore, all known orchid species are protected in several countries by regional, national and international legislation. Several studies have cast doubts on the effectiveness of legislation to ensure the protection of wild orchids. We assessed the vitality of four orchid populations in a coastal area in Northern Italy, by monitoring the vegetative and reproductive traits of the orchid populations growing both in the protected sites comprising the Natura 2000 network, and in non-protected sites. We also monitored the level of environmental threat to orchid vitality. The early-flowering deceptive species (Ophrys sphegodes and Anacamptis morio) exhibited high vegetative vitality and experienced similar levels of environmental threat in the protected and non-protected areas. However, their reproductive success was strongly jeopardized, probably by a failed pollination that impeded the fruit set. The late-flowering, partially or totally rewarding species (Anacamptis pyramidalis and Anacamptis coriophora) were more strongly impacted by spring mowing and ungulate herbivory and alien species. Only for A. coriophora were the herbivory and alien species invasions lower at the protected vs. non-protected sites, which ensured a higher population vitality at the protected sites. We conclude that the environmental protection in our study area is ineffective for preserving orchids without targeted actions against specific environmental threats. Full article