Epiphytic Orchid Research Articles

Epiphytic orchids show specificity for phorophyte and strata on palm trees in a restinga area in the Brazilian Atlantic Forest

Epiphytic orchids show specificity for phorophyte and strata on palm trees in a restinga area in the Brazilian Atlantic Forest

Taxonomy of Coelogyne section Fuliginosae (Orchidaceae): new species, notes, resurrections and typifications

Coelogyne tripurensis is described here as a species new to science. This epiphytic orchid was discovered from the moist broadleaf forests of Jampui Hills in Tripura, North-East India situated at the westernmost fringe of Indo-Myanmar Biodiversity Hotspot. Evidences to delineate the newly described species and its significant differences from closely related taxa have been provided. We discuss the resurrection of C. fuliginosa, C. leungiana and C. pallens as distinct species. Additionally, lectotypification of C. chrysotropis, C. ovalis and C. pallens, and neotypification of C. fuliginosa is presented. We also provide historical evidence for the range extension of C. phitamii in Thailand. An identification key for the taxonomically challenging Coelogyne section Fuliginosae which consists of nine species is provided along with detailed nomenclatural notes on each species as a revision of the section.

The diversity of fungal associates of Dendrobium ovatum (L.) Kraenzl., an endemic orchid of the Western Ghats of India

Dendrobium ovatum is a tropical epiphytic orchid endemic to the Western Ghats of India and has been listed as a threatened species in recent research due to its declining populations and changes in flowering and fruit set patterns. This study aims to investigate the mycoflora associated with the roots, stems and leaves of D. ovatum. Both surface‐associated and endophytic fungal associates were isolated and identified using morphological and molecular methods. The study resulted in the isolation of 139 cultures, which were divided into 24 morphotypes, 99% of which belonged to Ascomycota. The most dominant members, Trichoderma harzianum and Colletotrichum gloeosporioides, were consistently observed across all the study sites. Tissue‐specific fungal diversity analysis revealed that each organ was dominated by a distinct fungal group, forming characteristic communities specific to each tissue. The roots of D. ovatum exhibited the highest species richness and diversity, compared to the stem and leaves. This research also represents the first documentation of fungal associates of the threatened orchid D. ovatum.

Effect of Different Basal Media and Organic Supplements on In Vitro Seedling Development of the Endangered Orchid Species Dendrobium moniliforme (L.) Swartz

The orchid Dendrobium moniliforme faces endangerment due to habitat loss and illegal harvesting, necessitating the development of an optimized artificial propagation system to aid conservation and reintroduction efforts. This study evaluated the effects of three plant growth media, namely Murashige and Skoog (MS), Hyponex, and Orchid Maintenance Medium (OMM) (P668), and various organic additives (apple homogenate, banana homogenate, and coconut water) on the in vitro seedling growth of D. moniliforme. The results reveal that, in early postgermination stages, seedlings achieve maximum growth in the Hyponex medium, with a fresh weight (92 mg) and root length (2.7 cm) approximately 20-fold greater than those in the MS medium and OMM. After 6 months, for seedlings grown in MS medium and OMM with banana (50 g·L−1), the mean fresh weights were 29 and 107 mg, respectively; however, the highest biomass was observed in seedlings grown in the Hyponex medium with coconut water (50 mL·L−1), exhibiting a mean fresh weight of 201 mg. This study highlights Hyponex medium with coconut water as the most effective combination for promoting D. moniliforme growth and identifies suitable organic supplements for the in vitro cultivation of seedlings from asymbiotic seed culture. This propagation system offers valuable technical support for the mass production and conservation of this epiphytic orchid.

Exploring the bacterial diversity of Dendrobium ovatum (L.) Kraenzl., a threatened orchid endemic to the Western Ghats of India: a preliminary report

ABSTRACT Dendrobium ovatum is an epiphytic orchid endemic to the Western Ghats of India. Due to its valuable medicinal and therapeutic properties, the plant has become extensively sought after, leading to its classification as ‘threatened’ in the latest research findings. The present study aims to identify the surface-associated and endophytic bacterial associates of Dendrobium ovatum, which may be of great significance from a conservation standpoint. The investigation resulted in isolating and identifying 21 bacterial isolates representing six genera from the absorption roots, stem, and leaves. Bacillus was the most dominant genus, with seven representative species from root and stem segments. Enterobacter formed the second most dominant genus, with four representatives from leaf and stem. Bacillus cereus was found to be the most prevalent species, with a relative frequency of 28.57%. Root segments were found to be the most diverse tissue compared to stem and leaves. The study concluded that each tissue represents a unique ecological niche harbouring specific bacterial associate. The study also illuminates the intricacies of the orchids’ microbial community structure and forms the first documentation of bacterial associates of the threatened endemic orchid D. ovatum.

Efficient Surface Sterilant for Establishment of Dendrobium in vitro Culture

Background: Most orchid species in the Dendrobium genus are epiphytic. Dendrobium orchid (Dendrobium nobile L.) var. Sonia is a non-woody epiphytic orchid that bears a beautiful purple-coloured flower and grows in soilless medium. Dendrobium can be propagated vegetatively through divisions or Keikis. But this propagation method is extremely slow. Micropropagation is most suitable method for multiplication of dendrobium orchids. Surface sterilization is an important step in the preparation of vigorous and viable explants in micropropagation. Most of the surface contaminants can be abolished by surface sterilization with a suitable sterilizing agent. The aim of the investigation is to present an effective disinfection method for the aseptic culture of Dendrobium var. Sonia by using nodal segments. Methods: In the present investigation, two sterilant were employed namely mercuric chloride (HgCl2) and sodium hypochlorite (NaOCl) at different concentrations and durations. A total of nine combinations were tried for treating nodal explants in this investigation during 2022-2023. Explants were surface sterilized with 70% ethanol for 5 minutes followed by 3 to 4 washes with sterile distilled water. Thereafter, the explants were subjected to different surface sterilization treatments to establish contamination free cultures. Result: The study revealed that among the 9 treatments, minimum contamination (30.40%) was recorded in 0.1% HgCl2 for 10 minutes which helps in the maximum establishment of healthy culture (69.60%). Whereas, the lowest result for establishment was found in autoclaved distilled water with maximum contamination (100%). Maximum explant mortality (20.80%) due to sterilant was observed in NaOCl (2%) for 20 minutes.

Plastome Evolution and Comparative Analyses of a Recently Radiated Genus Vanda (Aeridinae, Orchidaceae).

Vanda R.Br. is an epiphytic orchid genus with significant horticultural and ornamental value. Previous molecular studies expanded Vanda including some members from five other genera. However, the interspecific relationships of this recently radiated genus have remained unclear based on several DNA markers until now. In this study, the complete plastome has been used to infer the phylogenetic relationships of Vanda s.l. The five newly obtained plastomes ranged from 146,340 bp to 149,273 bp in length, with a GC content ranging from 36.5% to 36.7%. The five plastomes contained 74 protein-coding genes (CDSs), 38 tRNAs, and 8 rRNAs, and their ndh genes underwent loss or pseudogenization. Comparative plastome analyses of 13 Vanda species revealed high conservation in terms of genome size, structure, and gene order, except for a large inversion from trnGGCC to ycf3 in V. coerulea. Moreover, six CDSs and five non-CDSs were selected as candidate DNA barcodes. Our phylogenetic analyses demonstrated that Vanda s.l. is a monophyletic group with high supporting values based on five different datasets (complete plastome with one IR, 68 CDSs, LSC, five hypervariable non-CDSs, and six hypervariable CDSs), while the phylogenetic relationships among species were fully resolved based on the complete plastome with one IR dataset. Our results confirmed that the complete plastome has a great power in resolving the phylogenetic relationships of recently radiated lineages.

Diversity of Orchid species in the Tilu Mountains Region of Indonesia and the Potential for Phytochemistry

Orchids are one of the largest and globally distributed plant families. Indonesia has the most types of orchids, estimated around 20% from the total species across the world. Mainly orchids used as an ornamental plant. This research aimed to elucidate another potential of orchids as possibly for herbal medicine plant. The potential of orchids as herbal medicine has been known for a long time, but there is lack of well-documented research. The research method used in this research is exploration on predetermined research sites that were conducted in Mount Tilu, West Java on 2022. Observation data of orchids were collected on the sites and the analysis was carried out in a qualitative descriptive approach by describing the data from the research results and comparisons were made through a literature review. Based on the research results, we found about 31 species from 28 genera consisting of 24 epiphytic orchids and 7 terrestrial orchids in the Mount Tilu Kuningan area, West Java. There are 4 endemic species categorised in Java; Chilochista javanica, Crepidium koordesii, Crepidium junghuhnii, and Taeniophyllum biocellatum.

ORCHID DIVERSITY (Orchidaceae) IN TWO URBAN SITES IN THE STATE OF VERACRUZ, MEXICO

Knowledge of urban orchids and their phorophytes is essential for conservation and education initiatives in these areas. The objective of this study was to assess the diversity of epiphytic orchids and identify their phorophytes at Postgraduate College Campus Córdoba (CPCC) and Paso Coyol Ecological Park (PEPC) in order to better understand the differences in their composition. The hypothesis was that the diversity of naturally established orchids would be higher in the less urbanized area, while the phorophytes would be mostly introduced trees. Orchids growing on phorophytes of the garden area (12 000 m²) of both sites were quantified from November 2019 to December 2021. The origin (endemic, native, or exotic) of the orchids and their phorophytes were determined. Simpson and Shannon-Weaver diversity indices were applied, and Whittaker curves were developed. A total of 13 419 orchid individuals were recorded, divided into 31 species, with 26 species reported in the CPCC and 17 in the PEPC. The Simpson and Shannon-Weaver indices showed that the diversity of epiphytic orchids was higher in the CPCC (1-D = 0.78) than in the PEPC (1-D = 0.41). In contrast, species dominance was lower in the CPCC (H = 2.6) than in the PEPC (H = 1.16). Whittaker curves showed that Catasetum integerrimum was the most abundant species in the CPPC and Platystele stenostachya in the PEPC. The CPCC had a greater level of diversity. Fifteen species of phorophytes were recorded in the CPCC and 10 in the PEPC, with a predominance of exotic species, while introduced species accounted for 70 % of the phorophytes found.

Short Communication: Habitat preferences of epiphytic orchids and potential pollinators in Sumber Pawon Forest, Kediri District, East Java, Indonesia

Abstract. Putra SRT, Trisnawati I. 2024. Short Communication: Habitat preferences of epiphytic orchids and potential pollinators in Sumber Pawon Forest, Kediri District, East Java, Indonesia. Biodiversitas 25: 2780-2787. Sumber Pawon Forest, a unique and biodiverse ecosystem in Kediri, Indonesia, is home to approximately 30,000 orchids (family Orchidaceae), which can grow terrestrial or as epiphytes. A diversity of different taxa has been recorded as orchid pollinators. The distribution of epiphytic orchids in this forest is determined by habitat preferences including vertical distribution zone and host tree's characteristics. This research, conducted in the captivating Sumber Pawon Forest, aims to determine habitat preferences influencing the abundance of epiphytic orchids and provide a review of potential epiphytic orchid pollinators. The data were collected by systematic sampling method. Analysis of epiphytic orchids' habitat preferences was done using the ordination method. The study found 3 epiphytic orchids and 5 species of host trees, revealing new insights into their distribution. Epiphytic orchids include Cymbidium sp., Dendrobium crumenatum, and Rhynchostylis retusa. The host trees include Alstonia scholaris, Artocarpus elasticus, Bischofia javanica, Ficus elastica, and Samanea saman. Epiphytic orchids were mainly found in zone 4 rather than in zone 5. The characteristics of host trees, which are preferentially selected by epiphytic orchids, include tree height (ranging from 28.65 to 33.65 m), large DBH (ranging from 165.61 to 175.80 m), and closed canopy cover (ranging from 51 to 75%). One of the pollinator taxa (named Hymenoptera) was found to pollinate epiphytic orchid species, adding to our understanding of their ecological interactions.

The Complete Chloroplast Genome of an Epiphytic Leafless Orchid, Taeniophyllum complanatum: Comparative Analysis and Phylogenetic Relationships

Taeniophyllum is a distinct taxon of epiphytic leafless plants in the subtribe Aeridinae of Orchidaceae. The differences in chloroplast genomes between extremely degraded epiphytic leafless orchids and other leafy orchids, as well as their origins and evolution, raise intriguing questions. Therefore, we report the chloroplast genome sequence of Taeniophyllum complanatum, including an extensive comparative analysis with other types of leafless orchids. The chloroplast genome of T. complanatum exhibited a typical quadripartite structure, and its overall structure and gene content were relatively conserved. The entire chloroplast genome was 141,174 bp in length, making it the smallest known chloroplast genome of leafless epiphytic orchids. It encoded a total of 120 genes, including repetitive genes, comprising 74 protein-coding genes, 38 transfer RNA (tRNA) genes, and 8 ribosomal RNA (rRNA) genes. A phylogenetic analysis was conducted on the chloroplast genomes of 43 species belonging to five subfamilies of Orchidaceae. The results showed that the five subfamilies were monophyly, with nearly all segments having a 100% bootstrap value. T. complanatum and Chiloschista were clustered together as a sister group to Phalaenopsis and occupied the highest position in the Epidendroideae. Phylogenetic analysis suggested that T. complanatum and other leafless orchids within the Orchidaceae evolved independently. This study may provide the foundation for research on phylogenetic and structural diversity in leafless epiphytic orchids, thereby enhancing the resources available for chloroplast genome studies in Orchidaceae.

Diverse geotropic responses in the orchid family.

In epiphytes, aerial roots are important to combat water-deficient, nutrient-poor, and high-irradiance microhabitats. However, whether aerial roots can respond to gravity and whether auxin plays a role in regulating aerial root development remain open-ended questions. Here, we investigated the gravitropic response of the epiphytic orchid Phalaenopsis aphrodite. Our data showed that aerial roots of P. aphrodite failed to respond to gravity, and this was correlated with a lack of starch granules/statolith sedimentation in the roots and the absence of the auxin efflux carrier PIN2 gene. Using an established auxin reporter, we discovered that auxin maximum was absent in the quiescent center of aerial roots of P. aphrodite. Also, gravity failed to trigger auxin redistribution in the root caps. Hence, loss of gravity sensing and gravity-dependent auxin redistribution may be the genetic factors contributing to aerial root development. Moreover, the architectural and functional innovations that achieve fast gravitropism in the flowering plants appear to be lost in both terrestrial and epiphytic orchids, but are present in the early diverged orchid subfamilies. Taken together, our findings provide physiological and molecular evidence to support the notion that epiphytic orchids lack gravitropism and suggest diverse geotropic responses in the orchid family.

Diversity of orchid types in the Oeluan Tourism Forest, Bijeli Village, Noemuti District, North Central Timor Regency

Indonesia as a mega biodiversity country has a variety of fauna and flora. One of the floras that is often found in Indonesia is orchids. Orchids have high economic value and are able to balance the ecosystem in their habitat. This study was aimed at determining the diversity of orchid species in the Oeluan tourism forest. The current study employed a quantitative descriptive study by using the transect and the purposive sampling method. The research was conducted in February at the Oeluan Tourism Forest. The results of this study indicated that there were four terrestrial orchid genera and three epiphytic orchid genera. The analysis of the diversity index of orchid species in the Oeluan tourism forest resulted in the diversity index of (H’) 1.0438 in the medium category. The measured environmental factors at the study site were an average soil pH of 7, an average humidity of 76.33% and an average air temperature of 27.400C. The diversity of orchid species in the Oeluan tourism forest, bijeli village, Noemuti district, North Central Timor regency, East Nusa Tenggara Province, was included in the medium category.

Exploration and Characterization of Host Trees and Orchid Epiphyte Zones in Lore Lindu National Park, Central Sulawesi

Host trees are vital for the survival of epiphytic orchids, providing necessary light and air circulation for optimal growth. Large trees with tall canopies contribute to the broader distribution of epiphytic orchids in forest areas. This research aimed to identify the characteristics of orchid host tree species in Lore Lindu National Park, considering both elevation zones and orchid growth zones. The research was conducted at various locations within the park, employing the field exploration survey method (cruise method). This method involved comprehensive exploration at each research site and establishing observation paths along pioneer lines, mainly where orchid host trees were found. The findings indicate the presence of 20 types of orchid host trees and 35 species of epiphytic orchids. The basal branching zone (Zone 3) was the most populated by epiphytic orchids on host trees, and the lowland forest was the elevation zone where most orchid host trees were found in Lore Lindu National Park, Central Sulawesi. Keywords: host trees, Lore Lindu National Park, orchids, zone distribution

Host suitability for germination differs from that of later stages of development in a rare epiphytic orchid

We explore phorophyte suitability for germination and establishment of the epiphytic orchid, Psychilis kraenzlinii. We found that the orchid grows on a subset of the available tree species and shows preference for the endemic Machaonia portoricensis (Rubiaceae). The orchid preferred trees with smoother bark with high water holding capacity and low water retention capacity. Microclimatic conditions under which embryos began pre-germination stages mirrored that of the adult orchid, but germination did not, suggesting that suitable germination sites are not necessarily the best sites for later stages of development.

Associations between Epiphytic Orchids and Their Hosts and Future Perspectives of These in the Context of Global Warming

Epiphytic species are ecologically important and a significant component of biodiversity. To ensure their efficient conservation, we need to understand their ecology and host plant associations. It is also important to investigate how the predicted temperature change will affect their future distribution. Here, we use data collected in Nepal to investigate how epiphytic orchids are associated with host species, their distribution patterns, and how they may be threatened by the predicted increase in temperature towards the end of the 21st century. We used the phi coefficient (Φ) of association to calculate the associations of epiphytic orchid species with plants and rarefaction to describe the diversity of orchids associated with a particular host species. We used interpolation to estimate the distribution of epiphytic orchids and their host species along altitudinal gradients. The phi (Φ) coefficient of association revealed that 30 species of host plants showed more association with different orchid species than expected. The number of epiphytic orchids increased with the number of host individuals. We predict that an increase in temperature by ~3 °C, which is a more moderate value of temperature increase by the end of the 21st century, will affect at least 52 narrow-ranged species of orchids and 58 narrow-ranged species of host plants. Therefore, we should make efforts to prevent many plant species from becoming extinct, as an increase in temperature is likely to affect their existence.

Phorophyte preference of an epiphytic orchid (Dendrobium wangliangii) is independent of orchid mycorrhizal fungi that promote seed germination

Abstract Epiphytism is an example of an obligate interspecific interaction between plants, where a plant species grows on another plant species for physical support. In epiphytic orchids that rely on suitable host tree species (phorophytes) and mycorrhizal fungi for germination and growth, a distinct preference has been observed for particular host tree species. However, the factors driving this host preference remain unclear. In this study, we investigated whether mycorrhizal fungi that promote seedling development determine the preference of phorophytes in the epiphytic orchid Dendrobium wangliangii. First, we identified the preferred host tree species for this orchid. Next, in vitro and in situ germination experiments were conducted to identify potential fungi that promote seed germination. Finally, high‐throughput sequencing was used to assess the distribution of these fungi on both colonized host trees and potential host trees, including individual trees of the host species not yet colonized by the orchid and trees of another species growing in the vicinity of a colonized tree. Dendrobium wangliangii exhibited a preference for trees within the Fagaceae family. Two Fusarium species from the bark of host trees were identified as the primary fungi that promote seed germination. Successful protocorm formation and seedling development were observed exclusively on preferred phorophytes. Fungal community analyses further indicated that both Fusarium spp. occurred on all potential host trees, suggesting that the host preference of this epiphytic orchid is not constrained by the distribution of suitable mycorrhizal fungi. Synthesis: Regarding the epiphytes that depend on mycorrhizal fungi for successful seedling recruitment, we conclude that strong epiphyte–phorophyte associations do not arise from the limited distribution of mycorrhizal fungi but are more likely the result of other factors inherent in the phorophyte environment.

Mycorrhizal Fungi of Phalaenopsis japonica (Orchidaceae) and Their Role in Seed Germination and Seedling Development

Epiphytic orchids comprise 68% of vascular epiphytes globally; nevertheless, many are endangered. One such epiphytic orchid is Phalaenopsis japonica, which is widely used in the floricultural industry. This study aimed to identify the mycorrhizal fungi of adult P. japonica and their roles in seed germination and seedling development. Root samples were collected from 32 adults across 4 sites in southern Japan, and mycorrhizal fungi were identified using Sanger and high-throughput sequencing (HTS). The results show phylogenetically diverse mycobionts, mainly Ceratobasidiaceae (CE) and Tulasnellaceae (TU), with dominant OTUs designated CE6 and CE22. Sanger sequencing found 9 OTUs, 4 CE, and 5 TU; HTS detected 22 OTUs, 4 CE, 16 TU, and 2 Serendipitaceae. Seeds inoculated with CE6 improved germination and protocorm development compared with other strains. In addition, asymbiotic seedlings inoculated with CE6, CE22, and TU18 displayed varying effects in growth, with CE6 being the most notable. While TU18 did not promote seed germination, it effectively promoted leaf development in seedlings. Overall, Ceratobasidiaceae was predominantly associated with seed germination, seedling growth, and the adult stages, with CE6 and CE22 becoming the primary partners throughout the life history of P. japonica. Our findings illuminate mycorrhizal symbiosis in epiphytic habitats, offering conservation and commercial production insights.

Auxin production and plant growth promotion by Microbacterium albopurpureum sp. nov. from the rhizoplane of leafless Chiloschista parishii Seidenf. orchid.

The strains of the genus Microbacterium, with more than 150 species, inhabit diverse environments; plant-associated bacteria reveal their plant growth-promoting activities due to a number of beneficial characteristics. Through the performance of diverse techniques and methods, including isolation of a novel Microbacterium strain from the aerial roots of leafless epiphytic orchid, Chiloschista parishii Seidenf., its morphological and biochemical characterization, chemotaxonomy, phylogenetic and genome analysis, as well as bioassays and estimation of its auxin production capacity, a novel strain of ET2T is described. Despite that it shared 16S rRNA gene sequence similarity of 99.79% with Microbacterium kunmingense JXJ CY 27-2T, so they formed a monophyletic group on phylogenetic trees, the two strains showed clear divergence of their genome sequences. The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) values of ET2T differed greatly from phylogenetically close JXJ CY 27-2T. Based on the differences being below the threshold for species similarity, together with the unique chemotaxonomic characteristics, strain ET2T represents a novel species of the genus Microbacterium. Several genes, putatively involved in auxin biosynthesis were predicted. This strain revealed obvious plant growth-promoting activities, including diazotrophy and biosynthesis of tryptophan-dependent auxins (indole-3-acetic and indole-3-pyruvic acids). Microbial auxins directly stimulated the rhizogenesis, so that the ET2T-inoculated seeds of wheat, cucumber and garden cress showed evident promotion in their growth and development, both under optimal and under cold stress conditions. Based on phenotypic, chemotypic and genotypic evidences, the strain ET2T belongs to the genus Microbacterium, order Micrococcales, class Actinomycetes, and it represents a novel species, for which the name Microbacterium albopurpureum sp. nov. is proposed, with strain ET2T (VKPM Ac-2212, VKM Ас-2998) as the type strain.

Effects of Climate Change on the Distribution of Prosthechea mariae (Orchidaceae) and within Protected Areas in Mexico.

The impact of climate change on the distribution of native species in the Neotropics remains uncertain for most species. Prosthechea mariae is an endemic epiphytic orchid in Mexico, categorized as threatened. The objective of this study was to assess the effect of climate change on the natural distribution of P. mariae and the capacity of protected areas (PAs) to safeguard optimal environmental conditions for the species in the future. Historical records were obtained from herbaria collections and through field surveys. We utilized climate variables from WorldClim for the baseline scenario and for the 2050 period, using the general circulation models CCSM4 and CNRM-CM5 (RCP 4.5). Three sets of climate data were created for the distribution models, and multiple models were evaluated using the kuenm package. We found that the species is restricted to the eastern region of the country. The projections of future scenarios predict not only a substantial reduction in habitat but also an increase in habitat fragmentation. Ten PAs were found within the current distribution area of the species; in the future, the species could lose between 36% and 48% of its available habitat within these PAs. The results allowed for the identification of locations where climate change will have the most severe effects, and proposals for long-term conservation are addressed.