Orchid conservation: how can we meet the challenges in the twenty-first century?

Integrated plant conservation through the Global Conservation Consortia

The 2020 State of the World's Plants and Fungi report revealed that two in five plant species are threatened with extinction. Despite their diverse ecosystem services and myriad human uses, plants receive a fraction of the conservation resources directed at animal taxa. Several existing frameworks-including International Union for Conservation of Nature (IUCN) Specialist Groups, the American Public Gardens Association Plant Collections Network, and the Center for Plant Conservation National Collection of Endangered Plants-have spurred conservation action, but there remains an urgent need to scale up conservation efforts for the world's plants. Here, a new approach to coordinated conservation action for plant taxa is described: the Global Conservation Consortia (GCC). GCC catalyze institutions and experts to collaboratively develop and implement comprehensive strategies to prevent extinction of threatened plant groups. This review focuses on three tree-focused, U.S.-led consortia: cycads, magnolias, and oaks, but the GCC framework is applicable to other taxonomic groups. This review covers consortia design and implementation, provides conservation action case studies, and shares preliminary successes and challenges as this new and exciting approach to conservation is developed.

How Effective Is Environmental Protection for Ensuring the Vitality of Wild Orchid Species? A Case Study of a Protected Area in Italy

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.

Diversity of Mycorrhizal Fungi in Temperate Orchid Species: Comparison of Culture-Dependent and Culture-Independent Methods

Many orchid species are endangered due to anthropogenic pressures such as habitat destruction and overharvesting, meanwhile, all orchids rely on orchid mycorrhizal fungi (OMF) for seed germination and seedling growth. Therefore, a better understanding of this intimate association is crucial for orchid conservation. Isolation and identification of OMF remain challenging as many fungi are unculturable. In our study, we tested the efficiency of both culture-dependent and culture-independent methods to describe OMF diversity in multiple temperate orchids and assessed any phylogenetic patterns in cultivability. The culture-dependent method involved the cultivation and identification of single pelotons (intracellular hyphal coils), while the culture-independent method used next-generation sequencing (NGS) to identify root-associated fungal communities. We found that most orchid species were associated with multiple fungi, and the orchid host had a greater impact than locality on the variability in fungal communities. The culture-independent method revealed greater fungal diversity than the culture-dependent one, but despite the lower detection, the isolated fungal strains were the most abundant OMF in adult roots. Additionally, the abundance of NGS reads of cultured OTUs was correlated with the extent of mycorrhizal root colonization in orchid plants. Finally, this limited-scale study tentatively suggests that the cultivability character of OMF may be randomly distributed along the phylogenetic trees of the rhizoctonian families.

Orchid Micropropagation Using Temporary Immersion Systems: A Review

Temporary immersion systems (TIS) have been used for orchid micropropagation. The main advantage of TIS use for micropropagation is that the explant is periodically immersed in nutrient media, and then, the nutrient solution is drained, which allows the explant tissue to stay in air. The current review resumes the application of TIS in orchid propagation. Fifty-three papers are discussed considering: explant, culture media, TIS bioreactor type, frequency and immersion time, and the TIS effects in acclimatization phase.

Symbiotic seed germination and seedling growth of mycorrhizal fungi in Paphiopedilum hirsutissimun (Lindl.Ex Hook.) Stein from China

Similar to other orchid species, Paphiopedilum hirsutissimum (Lindl.ex Hook.) Stein, relies on nutrients provided by mycorrhizal fungus for seed germination and seedling development in the wild owing to a lack of endosperm in its seeds. Therefore, obtaining suitable and specialized fungi to enhance seed germination, seedling formation, and further development is considered a powerful tool for orchid seedling propagation, reintroduction, and species conservation. In this study, we investigated the diversity, abundance, and frequency of endophytic fungal strains in the root organs of P. hirsutissimum. One family and five genera of the fungi were isolated and identified through rDNA-ITS sequencing. The ability of isolated fungi to germinate in vitro from the seeds of this species was evaluated, and the development of P. hirsutissimum protocorm has been described. The findings showed that the treatments inoculated with endophytic fungal DYXY033 may successfully support the advanced developmental stage of seedlings up to stage 5. In addition, scanning electron microscopy (SEM) revealed that the mycelium of this strain began to invade from either end of the seeds up to the embryo, extending rapidly from the inside to the outside. Its lengthening resulted in the bursting of the seed coat to form protocorms, which developed into seedlings. The results showed that DYXY033 has a high degree of mycobiont specificity under in vitro symbiotic seed germination conditions and is a representative mycorrhizal fungus with ecological value for the species. In summary, this strain may particularly be significant for the protection of P. hirsutissimum species that are endangered in China. In the long run, it may also contribute to global efforts in reintroducing orchid species and in realizing in situ restorations of threatened orchid populations.

Taxonomic Identification and Molecular DNA Barcoding of Collected Wild-Growing Orchids Used Traditionally for Salep Production

Molecular DNA barcoding combined with botanical taxonomy can be used for the identification and conservation of collected Greek orchids used for salep production as well as in the regulation of fair salep trade. A modified CTAB protocol was used for DNA extraction, amplification of barcoding regions (ITS, matK, rbcL, trnH-psbA), and sequencing. Sequencing data were assembled using Bioedit software, and the BLAST algorithm was used on the NCBI database for species identification at the genus level. Molecular barcoding data based on genetic similarity identification was in full coherence with taxonomic classification based on morphological data. The combination of ITS and matK exhibited a greater capacity to identify a species among the Greek salep samples. Out of the 53 samples examined, 52.9% were classified as Dactylorhiza spp. and 33.3% as Anacamptis spp., whereas only 6 samples were identified as Orchis spp. (11.8%). Given that a superior-quality salep beverage comes from tubers of the latter, the number of samples classified as such in northwestern Greece is unexpectedly low. A database of 53 original reference sequences from wild-growing samples of Greek origin was generated, providing a valuable resource for the identification of other salep samples from different regions. The DNA barcoding results unveiled that salep samples from northwestern Greece are related to nine members of four different genera of Orchidaceae. All species are nationally protected and covered by the CITES convention, while many of these orchids are included in the EU Directive 92/43/EEC appendix as "Other Important Species". Thus, expedited coordinated management actions are needed to ensure their survival in the future.

Fungal Community Composition at the Last Remaining Wild Site of Yellow Early Marsh Orchid (Dactylorhiza incarnata ssp. ochroleuca)

The yellow early marsh orchid (Dactylorhiza incarnata ssp. ochroleuca) is a critically endangered terrestrial orchid in Britain. Previous attempts to translocate symbiotic seedlings to a site near the last remaining wild site demonstrated some success, with a 10% survival rate despite adverse weather conditions over a two-year period. However, to facilitate future reintroduction efforts or conservation translocations, a more comprehensive understanding of the fungal microbiome and abiotic soil characteristics at the final remaining wild site is required. Obtaining comprehensive information on both the fungal community and soil nutrient composition from wild sites has significant benefits and may prove critical for the success of future conservation translocations involving threatened orchids. This preliminary study, conducted at the last remaining wild site, revealed a significant correlation between the relative abundance of the orchid mycorrhizal fungal order Cantharellales and the concentrations of nitrate and phosphate in the soil. Another orchid mycorrhizal fungal group, Sebacinales, was found to be distributed extensively throughout the site. The composition of fungal communities across the entire site, orchid-hosting and non-orchid-hosting soils is discussed in relation to reinforcing the current population and preventing the extinction of this orchid.

Review of Orchidaceae of the northern part of Kazakhstan

We present a review of Orchidaceae Juss. of the northern part of Kazakhstan, within the steppe, forest-steppe and semi-desert habitats of the country (Pavlodar, northern Kazakhstan, Kostanay, Akmola, Aktobe, West Kazakhstan, partially Karaganda and East Kazakhstan regions). The investigation is based on herbarium materials, literature data and field observations. We examined material from the following herbarium collections: LE, MW, TK, MHA, SVER, KUZ, ALTB, AA, NUR, KG, KSPI, NS, NSK, MOSP, ORIS, PPIU, totalling 288 herbarium specimens. The paper presents data in the form of revision, focusing on orchids of the northern part of Kazakhstan. It is accompanied by maps indicating localities, notes on habitat preferences, phenology and conservation status. A total of 25 species of 16 genera were recorded, of which eight are included in the Red Book of Kazakhstan (2014). According to our data, we propose to enlarge the number of protected orchids by adding the following nine species: Corallorhizatrifida, Epipactisatrorubens, Gymnadeniaconopsea, Hammarbyapaludosa, Herminiummonorchis, Liparisloeselii, Malaxismonophyllos, Neottiacamtschatea and Spiranthesaustralis. The most widespread species in the studied region are Dactylorhizaincarnata, D.umbrosa and Epipactispalustris. The rarest species (single locality only) are Epipactisatrorubens, E.helleborine, Epipogiumaphyllum, Hammarbyapaludosa and Herminiummonorchis.

Interactions among mycorrhizal fungi enhance the early development of a Mediterranean orchid

Orchids depend on mycorrhizal fungi to germinate from seed. While multiple orchid mycorrhizal (OrM) taxa are often found associated with adult orchids, the relative contribution of particular OrM taxa to germination and early orchid development is poorly understood. We isolated 28 OrM fungi associated with the Mediterranean orchid Anacamptis papilionacea and tested the efficiency of five isolates on germination and early development, four belonging to the Tulasnella calospora species complex and one belonging to Ceratobasidium. Co-cultures of varying two-way and three-way combinations of OrM isolates were used in vitro to compare the simultaneous effect on seed germination rate with monocultures. We then tested whether, when given initial priority over other fungi, particular OrM taxa were more effective during the early stages of development. Seedlings germinated with different isolates were transferred to a growth chamber, and either the same or different isolate was added 45 days later. After 3 months, the number of roots, length of the longest root, and tuber area were measured. All OrM fungi resulted in seed germination; however, lower germination rates were associated with the Ceratobasidium isolate compared to the tulasnelloid isolates. There was significant decreased germination in co-culture experiments when the Ceratobasidium isolate was added. Despite being associated with reduced germination rates, the addition of the Ceratobasidium isolate to the seedlings germinated with tulasnelloid strains resulted in significant increased tuber size. Although A. papilionacea associates with many OrM taxa, these results show that OrM fungi may play different roles during orchid germination and early development. Even when given initial priority, other fungi may colonize developing orchids and interact to influence early orchid development.

Global conservation prioritization for the Orchidaceae

Quantitative assessments of endemism, evolutionary distinctiveness and extinction threat underpin global conservation prioritization for well-studied taxa, such as birds, mammals, and amphibians. However, such information is unavailable for most of the world's taxa. This is the case for the Orchidaceae, a hyperdiverse and cosmopolitan family with incomplete phylogenetic and threat information. To define conservation priorities, we present a framework based on phylogenetic and taxonomic measures of distinctiveness and rarity based on the number of regions and the area of occupancy. For 25,434 orchid species with distribution data (89.3% of the Orchidaceae), we identify the Neotropics as hotspots for richness, New Guinea as a hotspot for evolutionary distinctiveness, and several islands that contain many rare and distinct species. Orchids have a similar proportion of monotypic genera as other Angiosperms, however, more taxonomically distinct orchid species are found in a single region. We identify 278 species in need of immediate conservation actions and find that more than 70% of these do not currently have an IUCN conservation assessment and are not protected in ex-situ collections at Botanical Gardens. Our study highlights locations and orchid species in urgent need of conservation and demonstrates a framework that can be applied to other data-deficient taxa.

A novel method to produce massive seedlings via symbiotic seed germination in orchids

Orchids produce large numbers of dust-like seeds that rely heavily on orchid mycorrhizal fungi (OMFs) for germination. Using OMFs to facilitate orchid proliferation is considered an effective method for orchid conservation but still presents challenges in practice. In this study, orchid seed-fungus complexes, in which orchid seeds and fungal mycelia were embedded together to form granules, were developed as platforms to facilitate seed germination and seedling production. Overall, seedlings were produced by seed-fungus complexes for five orchid species with large variations in the percentages of seedlings produced among species/treatments. For the different fungal treatments in Dendrobium officinale, Sebacinales LQ performed much better than the other fungal strains. At 90 days after sowing, 75.8±2.6% seedlings were produced in the LQ treatment, which was significantly higher than in the Tulasnella sp. JM (22.0±3.0%) and Tulasnella sp. TPYD-2 (5.3±1.0%) treatments, as well as in the LQ and TPYD-2 cocultured treatment (40.4±3.2%), while no seedlings were formed in the Tulasnella sp. SSCDO-5 or control treatments. For the other four orchid species, only one compatible fungus for each species was used, and the percentages of seedlings in epiphytic Dendrobium devonianum (67.2±2.9%) and D. nobile (38.9±2.8%) were much higher than those in terrestrial Paphiopedilum spicerianum (2.9±1.1%) and Arundina graminifolia (6.7±2.1%) at 90 days after sowing. Adding 1% polymer water-absorbent resin to the seed-fungus complexes of D. officinale seeds with fungal strain Sebacinales LQ significantly increased seedling formation, while other additional substances showed negative effects on seedling formation. For the storage of seed-fungus complexes, it is recommended to store the seed-fungus complexes in valve bags at room temperature for a short time and at a low temperature of 4°C for no more than 30 days. As a platform for symbiotic seed germination, the seed-fungus complex can facilitate seed germination, produce seedlings and support subsequent seedling growth, and its seedling productivity depends on seed germination characteristics, seed viability, and the efficiency of fungi. Seed-fungus complexes have great potential to be used as propagules in orchid conservation.

Hybridization in the Fringed Orchids: An Analysis of Species Boundaries in the Face of Gene Flow

Natural hybridization between closely related species in sympatry is an evolutionary process that is common in orchids. Once seen as a threat to parent species, interspecific genetic change is increasingly viewed as a source of novel variation in some ecological contexts. Terrestrial fringed orchids in the genus Platanthera contain several clades with high genetic compatibility among species and many putative hybrids. We used biallelic SNPs generated with 3RAD sequencing to study the hybrid complex formed from the parent species P. blephariglottis, P. ciliaris, and P. cristata with high resolution. The genetic structure and phylogenetic relationship of the hybrid complex revealed site-dependent gene flow between species. We documented extensive hybridization and cryptic hybrids in sympatric sites. Interspecific genetic exchange is particularly common between P. blephariglottis and P. ciliaris, with cryptic hybrids among putative P. ciliaris samples being more common than parental assignments in sympatric sites. Hybridization across the triad species complex can reticulate lineages and introduce adaptive alleles. Conversely, it can reduce diversification rates and introduce maladaptive alleles. Investigation into whether anthropogenic forces are eroding species boundaries, particularly the permeable P. blephariglottis and P. ciliaris boundary, is appropriate for conservation efforts.

Orchid Micropropagation Using Conventional Semi-Solid and Temporary Immersion Systems: A Review

Orchids, with their astonishingly stunning flowers, dominate the international floricultural market. They are considered prized assets for commercial applications in pharmaceutical and floricultural industries as they possess high therapeutic properties and superior ornamental values. The alarming depletion of orchid resources due to excessive unregulated commercial collection and mass habitat destruction makes orchid conservation measures an extreme priority. Conventional propagation methods cannot produce adequate number of orchids, which would meet the requirement of these ornamental plants for commercial and conservational purposes. In vitro orchid propagation using semi-solid media offers an outstanding prospect of rapidly producing quality plants on a large scale. However, the semi-solid (SS) system has shortcomings with low multiplication rates and high production costs. Orchid micropropagation using a temporary immersion system (TIS) overcomes the limitations of the SS system by reducing production costs and making scaleup and full automation possible for mass plant production. The current review highlights different aspects of in vitro orchid propagation using SS and TIS and their benefits and drawbacks on rapid plant generation.

Ecological and habitat ranges of orchids in the northernmost regions of their distribution areas: A case study from Ural Mountains, Russia

The Orchidaceae, which is one of the most interesting families of angiosperms, contains a large number of rare species. Despite their acknowledged importance, little attention has been paid to the study of orchids distributed in northern territories. In this study, we determined the syntaxonomical diversity and ecological parameters of orchid habitats in two of Europe's largest protected areas, the Pechoro-Ilychsky Reserve and the Yugyd Va National Park (northeastern European Russia), and then compared our findings to those in other parts of orchid distribution ranges. For this purpose, we studied 345 descriptions of plant communities (releves) containing species from Orchidaceae and defined habitat parameters using Ellenberg indicator values with the community weight mean approach, nonmetric multidimensional scaling (NMS), and relative niche width. We found that orchids were distributed in eight habitat types and 97 plant associations. The largest number of orchid species is found in forest communities. Half of the orchid species under study occur in the mires and rock habitats with open vegetation. Several orchids consistently occur in areas disturbed by human activity. In addition, our study indicates that the main drivers of orchid distribution across the vegetation types are light and soil nitrogen. Our analysis of the ecological parameters of orchid habitats indicates that some orchid species can be classified as habitat specialists that are confined to a relatively narrow ecological niche in the Urals (e.g., Goodyera repens, Cypripedium guttatum and Dactylorhiza maculata). Several other species (e.g. Neottia cordata and Dactylorhiza fuchsia) grow under diverse ecological parameters.

Symbiotic Seed Germination and Seedling Development of Epidendrum geminiflorum Knuth from Ecuador

A greater understanding of the relationship between native orchids and their mycorrhizal symbionts is needed to ensure more effective orchid conservation strategies. A protocol for symbiotic seed germination and seedling development was developed for E. geminiflorum. Mature seeds were collected from a naturally occurring orchid population in Ecuador. Putative mycorrhizal fungi isolated from other native orchid species were used to screen their ability to facilitate germination and seedling development in vitro in either a 0/24 h or 12/12 h light/dark photoperiod at 20 °C. The mycorrhizal fungus Tulasnella calospora (UAMH 9824) isolated from Spiranthes brevilabris in Florida, USA, was also included in this study. Sterilization treatments using 0.3%, 0.5% sodium hypochlorite/ethanol or 2% calcium hypochlorite were tested for their effectiveness as sterilant and their subsequent effects on seed germination percentage. Effective surface seed sterilization was achieved with either 0.5% NaClO/ethanol or 2% calcium hypochlorite. However, significantly higher percentages of germinated embryos developed into protocorms when NaOCl solutions were used compared to the other treatments. Seed germination occurred in both photoperiods tested; however, delayed germination was observed under complete darkness. Seeds of E. geminiflorum germinated without fungal inoculation; however, co-culture with Tulasnella strains improved germination significantly. Seedling development was only observed when seeds were cultured in asymbiotic medium or co-cultured with T. caloscopa (UAMH 9824). Significantly longer seedlings were obtained when T. calospora was present in the culture compared with seedlings cultured in asymbiotic medium. The establishment of mycorrhizal associations was confirmed by the presence of pelotons in the roots of E. geminiflorum seedlings.

Auxin biosynthesis by Microbacterium testaceum Y411 associated with orchid aerial roots and their efficacy in micropropagation

Root-associated bacteria strongly affect plant growth and development by synthesizing growth regulators and stress-relieving metabolites. The present study is mainly focused on assessing aerial root-associated bacteria of Rhynchostylis retusa (L.) Blume is an endemic epiphytic orchid responsible for auxin production and influencing plant growth. A bacterial isolate, Microbacterium testaceum Y411, was found to be the most active producer of indole-3-acetic acid (IAA). The maximum IAA production (170µg/mL) was recorded with the bacterium at optimum process parameters such as pH 7, temperature 30°C, and tryptophan 1000 µg/mL in a culture medium for 48 h. The extracted auxin was purified and analyzed by FT-IR, HPLC, and HR-MS, indicating bacterial auxin has a similar mass value to 4-chloroindole-3-acetic acid auxin. Furthermore, the bacterial auxin was tested on in vitro propagation of orchid, Cymbidium aloifolium, and 90% seed germination was recorded in Murashige and Skoog's medium supplemented with bacterial auxin. The novel results obtained in this study are used for agricultural applications and the Microbacterium testaceum Y411 is a valuable biotechnological resource for a natural auxin.

Delimiting species in the taxonomically challenging orchid section Pseudophrys: Bayesian analyses of genetic and phenotypic data

Accurate species delimitation is critical for biodiversity conservation. Integrative taxonomy has been advocated for a long time, yet tools allowing true integration of genetic and phenotypic data have been developed quite recently and applied to few models, especially in plants. In this study, we investigated species boundaries within a group of twelve Pseudophrys taxa from France by analyzing genetic, morphometric and chemical (i.e., floral scents) data in a Bayesian framework using the program integrated Bayesian Phylogenetics and Phylogeography (iBPP). We found that these twelve taxa were merged into four species when only genetic data were used, while most formally described species were recognized as such when only phenotypic (either morphometric or chemical) data were used. The result of the iBPP analysis performed on both genetic and phenotypic data supports the proposal to merge Ophrys bilunulata and O. marmorata on the one hand, and O. funerea and O. zonata on the other hand. Our results show that phenotypic data are particularly informative in the section Pseudophrys and that their integration in a model-based method significantly improves the accuracy of species delimitation. We are convinced that the integrative taxonomic approach proposed in this study holds great promise to conduct taxonomic revisions in other orchid groups.

Plant Conservation vs. Folk Traditions: The Case of Ophrys scolopax Cav. (Orchidaceae) in Central Western Spain

In central western Spain, the bee orchid Ophrys scolopax Cav. is limited to a few localities of the Arribes del Duero Natural Park, reaching the municipality of Villarino de los Aires (Salamanca) to the north. Due to its restricted distribution, this plant is hardly known in this territory, with the exception of this village, where it is very popular. Although most of its inhabitants are unaware of various aspects of the biology of this orchid, for example its pollination strategy, the place where the only local population grows is well-known: the Teso de San Cristóbal ("St. Christopher's Hill"), a place of ancient pagan rituals Christianised through the construction of a hermitage. The villagers also know that its flowering period coincides with the Easter celebration, and they have traditionally looked for and collected it there during Easter Monday. This ritual has evolved over time based on the needs and interests of the community. From a religious celebration aimed at blessing the fields, it became a game among young men to obtain prestige within the community, and from the end of the 20th century to the present, it has become a festival to revitalise cultural identity. In this article, we analyse how the aforementioned traditional practices affected this orchid species in the recent past, and we describe the educational actions (conferences, workshops, courses, etc.) carried out during the last ten years so that, while maintaining the cultural practices of the village, its population should be respected and conserved at the same time.

Modeling the effect of climate change on the distribution of threatened medicinal orchid Satyrium nepalense D. Don in India

It is vital to understand the distribution area of a threatened plant species for its better conservation and management planning. Satyrium nepalense (family: Orchidaceae) is a threatened terrestrial orchid species with valuable medicinal and nutritional properties. The survival of S. nepalense in wild conditions has been challenged by increasing global surface temperature. Hence, understanding the impact of climate change on its potential distribution is crucial to conserve and restore this species. In present study, Maxent species distribution modeling algorithm was used to simulate the current distribution of S. nepalense in India and predict the possible range shift in projected future climate scenarios. A set of 19 bioclimatic variables from WorldClim database were used to predict the potential suitable habitats in current climatic condition and four Representative Concentration Pathway (RCP 2.6, 4.5, 6.0, and 8.5) scenarios by integrating five General Circulation Models (GCMs) for future distribution modeling of species for the years 2050 and 2070. Furthermore, change analysis was performed to identify the suitable habitat in current and future climate for delineating range expansion (gain), contraction (loss), and stable (no change) habitats of species. The Maxent model predicted that ~ 2.38% of the geographical area in India is presently climatically suitable for S. nepalense. The key bioclimatic variables affecting the distribution of studied species were the mean temperature of warmest quarter, mean temperature of wettest quarter, precipitation of warmest quarter, and temperature seasonality. Under future climate change scenarios, the total suitable habitat of S. nepalense will increase slightly in the Himalayan region and likely to migrate towards northward, but in the Western Ghats region, the suitable areas will be lost severely. The net habitat loss under four RCP scenarios was estimated from 26 to 39% for the year 2050, which could further increase from 47 to 60% by the year 2070. The finding of the predictive Maxent modeling approach indicates that warming climates could significantly affect the potential habitats of S. nepalense and hence suitable conservation measures need to be taken to protect this threatened orchid species in wild conditions.

Advances and prospects of orchid research and industrialization

Orchidaceae is one of the largest, most diverse families in angiosperms with significant ecological and economical values. Orchids have long fascinated scientists by their complex life histories, exquisite floral morphology and pollination syndromes that exhibit exclusive specializations, more than any other plants on Earth. These intrinsic factors together with human influences also make it a keystone group in biodiversity conservation. The advent of sequencing technologies and transgenic techniques represents a quantum leap in orchid research, enabling molecular approaches to be employed to resolve the historically interesting puzzles in orchid basic and applied biology. To date, 16 different orchid genomes covering four subfamilies (Apostasioideae, Vanilloideae, Epidendroideae, and Orchidoideae) have been released. These genome projects have given rise to massive data that greatly empowers the studies pertaining to key innovations and evolutionary mechanisms for the breadth of orchid species. The extensive exploration of transcriptomics, comparative genomics, and recent advances in gene engineering have linked important traits of orchids with a multiplicity of gene families and their regulating networks, providing great potential for genetic enhancement and improvement. In this review, we summarize the progress and achievement in fundamental research and industrialized application of orchids with a particular focus on molecular tools, and make future prospects of orchid molecular breeding and post-genomic research, providing a comprehensive assemblage of state of the art knowledge in orchid research and industrialization.

Ceratobasidium orchid mycorrhizal fungi reveal intraspecific variation and interaction with different nutrient media in symbiotic germination of Prasophyllum (Orchidaceae)

Understanding how nutrient requirements of orchid mycorrhizal fungi (OMF) affect symbiotic germination is essential for the ex situ conservation of threatened orchids and their mycorrhizal symbioses. Yet the influence of isolate-level variation in OMF nutrient preferences on orchid germination is unknown. We tested germination of Prasophyllum frenchii (Orchidaceae) on 15 different media of varying carbon and macronutrient compositions with three Ceratobasidium isolates of the same operational taxonomic unit (OTU) as determined with internal transcribed spacer locus sequencing. There was a significant interaction between media and fungal isolate on percentage germination, with each isolate recording its highest percentage germination on different nutrient media (Isolate 9.3: 5.2 ± 1.4% on MOM–S; Isolate 8.2: 5.4 ± 1.1% on MOM + S; Isolate 4.3: 2.2 ± 0.5% on 1.25 g/L wheat bran agar). Across all isolates, germination (percentage germination > 0) occurred more frequently on wheat bran agar media (39.7% of plates) than on oatmeal agar media (6.0% of plates). There was also an effect of media type on aerial hyphal growth behaviour of the OMF isolate. All isolates supported growth through to adult flowering plants. We demonstrated that symbiotic germination of Prasophyllum is affected by media composition. Further, percentage germination and aerial hyphal growth behaviour differed significantly among OMF isolates of the same OTU. This illustrates that a diversity of functionally significant fungal strains occurs within a single OTU, a previously unknown aspect of OMF research with important ecological and conservation implications.

The challenges of growing orchids from seeds for conservation: An assessment of asymbiotic techniques

Lewis Knudson first successfully germinated orchid seeds asymbiotically on artificial medium in 1922. While many orchid species have since been grown asymbiotically, the tremendous variation in how species respond to artificial medium and growth conditions ex situ has also become apparent in the past century. In this study, we reviewed published journal articles on asymbiotic orchid seed germination to provide a summary of techniques used and to evaluate if these differ between terrestrial and epiphytic species, to identify areas where additional research is needed, and to evaluate whether asymbiotic germination could be used more often in ex situ conservation. We found articles reporting successful asymbiotic germination of 270 species and 20 cultivars across Orchidaceae. Researchers often used different techniques with epiphytic versus terrestrial species, but species-specific responses to growth media and conditions were common, indicating that individualized protocols will be necessary for most species. The widespread success in generating seedlings on artificial media suggests that asymbiotic techniques should be another tool for the conservation of rare orchid species. Further advances are needed in understanding how to introduce mycorrhizae to axenically grown orchids and to maximize the viability of seedlings reintroduced into natural habitats to fully utilize these methods for conservation.

Janaki Rao, J. Prakasa Rao, S.B. Padal, C. Sudhakar Reddy. Pelatantheria insectifera (Rchb.f.) Ridl. (Orchidaceae): a new generic record for Eastern Ghats of Andhra Pradesh, India

The monopodial orchid Pelatantheria insectifera is reported here as a new generic record for the state of Andhra Pradesh (India). Further, detailed diagnostic description, colour photo plates for easy identification and note on ecology were provided.

Mesoamerican Cypripedium: Mycorrhizal Contributions to Promote Their Conservation as Critically Endangered Species

In the valuable orchid genus Cypripedium, the section Irapeana consists of a distinctive group of Mesoamerican species that is formed by Cypripedium dickinsonianum Hágsater, C. irapeanum Lex., and C. molle Lindl. All lady slipper orchids exhibit different distributions and abundances. Data analysis that used herbarium accessions and field investigations indicated that the habitats of these three species have been dramatically reduced. Prospecting for suitable habitats based on climatic, vegetation, and soil parameters allows us to predict potential distributions. Conservation strategies, such as ex situ propagation by asymbiotic and symbiotic approaches, have indicated that the culture media used are a determining factor for seedling development. Mycorrhizal isolates play a main role in the compatibility and further development of germinated seeds. The fungi isolated from adult plants belong to two different families, which makes it possible that widely distributed C. irapeanum populations will be fungal-specific as well as restricted for C. molle. Root mycorrhization patterns occur high on the secondary roots. In contrast with other species of the genus, in situ germination can occur over a short period of two months, but we have documented periods as long as ten years. Cypripedium is a highly problematic genus for ex situ conservation because the germination requirements and cultures are poorly documented, and there is great urgency for in situ conservation to develop strategies for identifying hotspot habitats and actualize the protection status to avoid extinction of this genus.

A Machine Learning Approach for the Non-Destructive Estimation of Leaf Area in Medicinal Orchid Dendrobium nobile L

In this study, leaf area prediction models of Dendrobium nobile, were developed through machine learning (ML) techniques including multiple linear regression (MLR), support vector regression (SVR), gradient boosting regression (GBR), and artificial neural networks (ANNs). The best model was tested using the coefficient of determination (R2), mean absolute errors (MAEs), and root mean square errors (RMSEs) and statistically confirmed through average rank (AR). Leaf images were captured through a smartphone and ImageJ was used to calculate the length (L), width (W), and leaf area (LA). Three orders of L, W, and their combinations were taken for model building. Multicollinearity status was checked using Variance Inflation Factor (VIF) and Tolerance (T). A total of 80% of the dataset and the remaining 20% were used for training and validation, respectively. KFold (K = 10) cross-validation checked the model overfit. GBR (R2, MAE and RMSE values ranged at 0.96, (0.82–0.91) and (1.10–1.11) cm2) in the testing phase was the best among the ML models. AR statistically confirms the outperformance of GBR, securing first rank and a frequency of 80% among the top ten ML models. Thus, GBR is the best model imparting its future utilization to estimate leaf area in D. nobile.

'Fly to a Safer North': Distributional Shifts of the Orchid Ophrys insectifera L. Due to Climate Change

Numerous orchid species around the world have already been affected by the ongoing climate change, displaying phenological alterations and considerable changes to their distributions. The fly orchid (Ophrys insectifera L.) is a well-known and distinctive Ophrys species in Europe, with a broad distribution across the continent. This study explores the effects of climate change on the range of O. insectifera, using a species distribution models (SDMs) framework that encompasses different climatic models and scenarios for the near- and long-term future. The species' environmentally suitable area is projected to shift northwards (as expected) but downhill (contrary to usual expectations) in the future. In addition, an overall range contraction is predicted under all investigated combinations of climatic models and scenarios. While this is moderate overall, it includes some regions of severe loss and other areas with major gains. Specifically, O. insectifera is projected to experience major area loss in its southern reaches (the Balkans, Italy and Spain), while it will expand its northern limits to North Europe, with the UK, Scandinavia, and the Baltic countries exhibiting the largest gains.

Brief Pollination Assessment of a Critically Endangered Food-Deceptive Orchid (Cypripedium guttatum) Using a Network Approach

The translocation of orchids (Orchidaceae) cannot be successful if one is unaware of their effective pollinators and plant–pollinator interactions. Cypripedium guttatum is a generalized food-deceptive orchid, which is highly threatened in the Republic of Korea, thus, requiring immediate translocation actions. Although effective pollinators of the orchid are well known in China, little is known about the pollinators in the Republic of Korea and the ecological context in which the orchid can be successfully pollinated. To briefly assess the pollination of C. guttatum prior to translocation, we conducted a one-month survey of general pollination and the community-wide plant–pollinator network properties. Over 21 h of observation, we found that an effective pollinator of the orchid was the sweat bee Lasioglossum virideglaucum. The network was significantly specialized and modular, but not significantly nested. L. virideglaucum (pollinator) and Arabis gemmifera (plant) were determined to be keystone species, based on network metrics. A total of six network modules were identified and the flower colors of the plant species belonging to the C. guttatum module were purple, white, and yellow. After comparing the daily network patterns, we found that pollination of the orchid was accomplished when various flowering plant species bloom, and the nestedness value was high. This study revealed that high plant and pollinator richness could increase the chance that the deceptive orchid would be pollinated. Our study suggests that the network properties of this food-deceptive orchid community could provide useful insight into understanding the ecologically suitable habitat for the translocation of the highly threatened orchid species C. guttatum.

Seed viability testing for research and conservation of epiphytic and terrestrial orchids

BACKGROUND

Seed viability testing is essential in plant conservation and research. Seed viability testing determines the success of ex-situ conservation efforts, such as seed banking but commonly testing protocols of orchids lack consistency and accuracy, therefore, there is a need to select an appropriate and reliable viability test, especially when conducting comparative studies. Here, we evaluated the suitability of three seed viability tests, Evans blue test (EB), Fluorescein diacetate test (FDA) and Tetrazolium test (TTC), with and without sterilization, on seeds of 20 orchid species, which included five epiphytes and fifteen terrestrials, using both fresh seeds and seeds stored at - 18 ºC for 6 to 8 years.

RESULTS

We found that sterilization and lifeform of seeds affected seed viability across all tests but the storage time was not an influential factor. Sterilization negatively affected seed viability under EB and FDA test conditions but increased the detection of viable seeds in the TTC test in both epiphytic and terrestrial species. The EB test, when administered without sterilization provided the highest viability results. Being non-enzymatic unlike TTC and FDA tests, as expected, the EB test was the most reliable with similar results between sterilized and not sterilized seeds for most epiphytic and terrestrial species as well as when compared between groups.

CONCLUSIONS

The lifeform of the species and seed sterilization prior to testing are important influential factors in orchid seed viability testing. Since EB test was found to be reliable we recommend the EB test for seed viability assessment in orchids rather than the less reliable but commonly used TTC test, or the FDA test, which require more expensive and sophisticated instrumentation. Since storage time was not an influential factor in orchid seed viability testing, the recommendations of this study can be used for both fresh as well as long-term stored orchid seeds. This is helpful for research and especially for conservation measures such as seed banking. However, due to the species specificity of the bio-physiology of orchids, we call for comprehensive viability test assessment in the hyper diverse orchid family to be extended to a greater number of species to facilitate efficient conservation and research.

Advances in Breeding, Bioprospecting, and In Vitro Culture of Laelia Orchid Species

Orchids (Orchidaceae) are plants that are highly appreciated by their beautiful flowers worldwide. Moreover, they represent a source of metabolites with applications in medicine and biotechnology. Within the Orchidaceae family, the Laelia genus is a group of orchid species from the Neotropics and is probably one of the most representative genera of America. Laelia orchids are cultivated by their splendid flowers and are widely used in orchid breeding. Here, we revise the use of the Laelia genus in orchid breeding and metabolite bioprospecting. We also analyze the use of plant tissue culture (PTC) as an alternative to conventional propagation and as a strategy for the recovery of those Laelia species threatened with extinction. We summarize and discuss the recent advances in the application of different PTC techniques for mass multiplication based on asymbiotic germination, organogenesis, protocorm-like bodies development, and somatic embryogenesis, and the advances of in vitro conservation by cryoconservation and the use of slow-growth promoting hormones. Finally, we suggest future directions and venues in research for Laelia species.

How Does Deforestation Affect the Growth of Cypripedium (Orchidaceae) Species? A Simulation Experiment in Northeast China

Due to wild habitat destruction, Cypripedium is among the most endangered groups in China. Determining how Cypripedium respond to environmental changes is curial to their conservation. However, less is known about the effect of deforestation on the growth of Cypripedium. In this study, we selected four Cypripedium species in Northeast China, and conducted conservation-based transplantation simulating deforestation to explore the impact of increased light intensity on the growth of Cypripedium. After three years, the maximum net photosynthetic rate was decreased by 15.9%, 11.5%, 13.6% and 5.3% for C. calceolus L., C. guttatum Sw., C. macranthos Sw. and C.×ventricosum Sw., respectively, resulting in poor viability, manifesting as shorter and thinner shoots, and smaller leaves. Unexpectedly, no significant traits shifts were found in the roots across four species, which may be related to the long root lifespan and conservation. Our research confirmed that increased light intensity caused by deforestation would lead to an increase in respirate cost and a decrease in photosynthate accumulation, and consequently the recession of plant growth. Except for habitat loss, individual plant reduction caused by deforestation could be responsible for the population decline of Cypripedium.

Suitable habitat modelling using GIS for orchids in the Black Sea Region (North of Turkey)

Orchids are under continuous threat from many factors, especially human-sourced. Estimating the emerging threat factors linked to habitat losses is very important to understand the effects on biodiversity and to design protection strategies and protected areas. Field assessments and modelling were performed with the aim of determining areas where orchids may spread and to reveal priority areas to create a protection plan. Additionally, the aim was to contribute to development of protection strategies for taxa under threat. This study was performed in the Black Sea region located in the north of Turkey. A total of 40 taxa belonging to 15 Orchidaceae genera were collected. The field assessment process used topographic parameters and threat factors. Habitats where orchids are most commonly distributed comprise open areas, meadows, pastures, and forests. Additionally, the density of orchids was determined to be highest at altitudes from 400 to 1600 m. The highest risk factors for taxa in the region include grazing and trampling. Based on these results, suitable habitats were modelled and mapped according to the observed habitat requirements. The determined suitable habitats will represent the preliminary targets for ex situ protection programs where required. The maps revealed here are important for labeling areas with an estimated orchid density and for protection of these areas if necessary. Our field observations were compatible with the obtained maps. Additionally, we consider these maps to be very important in terms of determining areas where taxa will be spread in preliminary field studies.

Nectar Chemistry or Flower Morphology-What Is More Important for the Reproductive Success of Generalist Orchid Epipactis palustris in Natural and Anthropogenic Populations?

The aim of this study was to determine the level of reproductive success (RS) in natural and anthropogenic populations of generalist orchid Epipactis palustris and its dependence on flower structure and nectar composition, i.e., amino acids and sugars. We found that both pollinaria removal and female reproductive success were high and similar in all populations, despite differences in flower traits and nectar chemistry. Flower structures were weakly correlated with parameters of RS. Nectar traits were more important in shaping RS; although, we noted differentiated selection on nectar components in distinct populations. Individuals in natural populations produced nectar with a larger amount of sugars and amino acids. The sucrose to (fructose and glucose) ratio in natural populations was close to 1, while in anthropogenic ones, a clear domination of fructose and glucose was noted. Our results indicate that the flower traits and nectar composition of E. palustris reflect its generalist character and meet the requirements of a wide range of pollinators, differing according to body sizes, mouth apparatus, and dietary needs. Simultaneously, differentiation of nectar chemistry suggests a variation of pollinator assemblages in particular populations or domination of their some groups. To our knowledge, a comparison of nectar chemistry between natural and anthropogenic populations of orchids is reported for the first time in this paper.

Six-Year Demographic Study of the Terrestrial Orchid, Crepidium acuminatum: Implications for Conservation

Studies on population dynamics are helpful for understanding the factors determining population development and predicting the effects of disturbances, such as harvesting of plant species. In an investigation of the demography of a terrestrial medicinal orchid known as Crepidium acuminatum, the effects of harvesting on its population dynamics were recorded. Data on recruitment, growth and survival were collected in three populations of C. acuminatum over a 6-year period (2012–2017) in central Nepal. A matrix modeling method was used to determine the effect of different harvesting regimes on the population growth and survival of this species. Population growth rates (λ) of unharvested populations were relatively similar and stable in different years of the study. Harvesting significantly reduced λ. The results of this study indicate that the sustainable survival of a population that is subject to harvesting can only occur when it is either selective (only flowering individuals or only small amounts of vegetative individuals) or rotational (once every 3–5 or more years). This study demonstrates the necessity of using a sustainable method when harvesting natural populations. Our results are useful for developing efficient management strategies for this species. As each species has a different biology, similar studies are needed for other rare and/or economically important species in the Himalayan region and in other understudied parts of the world.

Orchid diversity in China: Recent discoveries

•The project, Orchid Diversity Survey in China, has been initiated by Department of Wildlife Conservation of National Forestry and Grassland Administration (DWC-NFGA) from 2019 to 2022.•During botanical investigation, approximately 30 new species and 10 newly recorded species have been discovered.

Epiphytic Orchid Diversity along an Altitudinal Gradient in Central Nepal

Epiphytic orchids are common in subtropical forests, but little is known about the factors that determine their diversity. We surveyed two sites (north-facing Phulchowki and south-facing Shivapuri hills), in the sub-tropical forest in the Kathmandu valley, central Nepal. Along five transects per site, spanning an altitudinal gradient of 1525–2606 m a.s.l., we recorded all epiphytic orchids and the host species on which they were growing. The data were analyzed using a generalized linear model (GLM) and redundancy analysis (RDA). Species richness significantly decreased with increasing altitude and was higher in larger hosts and in places with high temperature. Species composition was affected by altitude, distance from the forest edge, host type, and precipitation. This study indicates that the most important factors affecting epiphytic orchid diversity was altitude, even if other factors were associated with patterns in composition. The low-altitude habitats with high species diversity are the best places for epiphytic orchids in this region. The altitudinal species richness and patterns in composition revealed by this study provide a baseline for further studies on epiphytic orchids.

Orchids of Mongolia: Taxonomy, Species Richness and Conservation Status

Orchidaceae is a diverse, globally important plant family with high conservation assessment and prioritization requirements. The checklist of Orchidaceae in Mongolia was updated based on herbarium materials, literature, and field observations. Mongolian orchids were revised as comprising 26 taxa belonging to 14 genera with major updates were conducted on Herminium and Epipactis. In particular, H. alaschanicum, previously noted in the Alashan Gobi region, was added to the flora of Mongolia based on literature and type specimens. Epipactis helleborine and E. palustris were excluded from the Mongolian flora owing to the absence of herbarium specimens and wild collection from Mongolia. Assessment of all orchid species at the national level resulted in 1, 4, 7, 11, and 2 species as critically endangered (CR), endangered (EN), vulnerable (VU), near threatened (NT), and data deficient (DD), respectively, according to IUCN criteria. Species richness and conservation gap analyses of 970 georeferenced orchid records based on 0.5° × 0.5° grid cells across 16 phytogeographical regions of Mongolia, showed that four phytogeographical regions, Khangai, Khuvgul, Khentii and Mongolian Dauria, have a high number of orchids. Regrettably, most orchid-rich locations in Mongolia are not fully within protected areas, highlighting the need for protection management updates. Based on herbarium collections, we prepared grid distribution maps of the 26 taxa using 40 × 40 km2 grids. Photographs of 18 taxa taken during fieldwork were included, providing valuable information on species morphology and typical habitat.