CONCLUSIONS: In this review, we have discussed the untapped potential of orchid endophytic bacteria as a valuable reservoir of bioactive metabolites, offering significant contributions to plant growth promotion and disease protection in the context of sustainable agriculture. Orchidaceae is one of the broadest and most diverse flowering plant families on Earth. Although the relationship between orchids and fungi is well documented, bacterial endophytes have recently gained attention for their roles in host development, vigor, and as sources of novel bioactive compounds. These endophytes establish mutualistic relationships with orchids, influencing plant growth, mineral solubilization, nitrogen fixation, and protection from environmental stress and phytopathogens. Current research on orchid-associated bacterial endophytes is limited, presenting significant opportunities to discover new species or genetic variants that improve host fitness and stress tolerance. The potential for extracting bioactive compounds from these bacteria is considerable, and optimization strategies for their sustainable production could significantly enhance their commercial utility. This review discusses the methods used in isolating and identifying endophytic bacteria from orchids, their diversity and significance in promoting orchid growth, and the production of bioactive compounds, with an emphasis on their potential applications in sustainable agriculture and other sectors.

The Stelidium group is readily distinguished from all other members of the subgenus Stelis Panzer, 1806 by the combination of small body size ( 6 mm), pale maculations on the head adjacent to the inner margins of the compound eyes and laterally on the vertex in both sexes, and females with sternum 6 extended beyond tergum 6, the former with the dorsal lip trowel-shaped with the apex broadly rounded or subtruncate to more narrowly pointed. This monophyletic clade, which is endemic to North America, currently consists of members previously placed into two species groups: the permaculata group containing S. anasazi Parker & Griswold, 2013, S. ashmeadiellae Timberlake, 1941, S. permaculata Cockerell, 1898, and S. robertsoni Timberlake, 1941, and the palmarum group containing S. broemelingi Parker & Griswold, 2013, S. elongativentris Parker, 1987, and S. palmarum Timberlake, 1941; two additional species, S. herberti (Cockerell, 1916) from Mexico, and S. nyssonoides (Brues, 1903) from Texas, United States, have not been definitively placed in either species group. Two new species are herein described, one from southcentral British Columbia, Canada, the other from New Mexico, United States. A preliminary molecular phylogeny places both new species in the permaculata species group. In addition, S. herberti is also placed within the permaculata species group based on morphological similarity, sharing the multi-spotted maculation pattern on the terga. Based on molecular affinity, S. broemelingi also belongs to the permaculata species group. Because no type specimen for S. nyssonoides is seemingly available for examination, it is hereby considered nomen dubium until the specimen is found and its taxonomic status clarified in relation to the more recently described species in the permaculata species group. A key to females and diagnoses are provided for all known taxa.

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.

Gastrodia elata Blume, a fully mycoheterotrophic perennial plant of the family Orchidaceae, is a traditional Chinese herb with medicinal and edible value. Interestingly, G. elata requires symbiotic relationships with Mycena and Armillaria strains for seed germination and plant growth, respectively. However, there is no comprehensive summary of the symbiotic mechanism between fungi and G. elata. Here, the colonization and digestion of hyphae, the bidirectional exchange of nutrients, the adaptation of fungi and G. elata to symbiosis, and the role of microorganisms and secondary metabolites in the symbiotic relationship between fungi and G. elata are summarized. We comprehensively and deeply analyzed the mechanism of symbiosis between G. elata and fungi from three perspectives: morphology, nutrition, and molecules. The aim of this review was to enrich the understanding of the mutualistic symbiosis mechanisms between plants and fungi and lay a theoretical foundation for the ecological cultivation of G. elata.

Dactylorhiza hatagirea (D. Don) Soo, also known as Himalayan Marsh Orchid or Salam Panja, belongs to the Orchidaceae family. It is found in sub-alpine to alpine regions at 2500-5000 m above sea level. The present review aims to provide a comprehensive overview of the botany, phytochemistry, medicinal uses, toxicity, and conservation status of D. hatagirea and to find the research gaps to promote progress in studies of this orchid. Secondary metabolites, including alkaloids, terpenoids, flavonoids, phenolics, and saponins, were reported from the aerial and underground parts of this medicinal orchid. Several phytocompounds, such as dactylorhins A, B, C, D, and E and dactylose A and B, were isolated from the dried roots of D. hatagirea. A wide range of in vitro and in vivo assays was used to assess the biological properties of D. hatagirea, such as antirheumatic, anti-inflammatory, antiviral, diuretic, neuroprotective, antioxidant, wound healing, hypoglycemic, antitumor, antimicrobial, antiviral, and anticancer activities. It was also reported to boost testosterone levels, improving sexual desire and arousal. Due to overexploitation and a restricted habitat range, this essential medicinal plant has reached the extinction stage; therefore, a conservation-friendly harvesting approach is needed for this medicinal herb. In vitro techniques such as micropropagation, synthetic seed generation, and hairy root technology can contribute to its conservation. This review provides comprehensive insights into the botanical features, traditional uses, phytochemicals, pharmacological importance, and toxicity evaluation of this medicinal orchid. This review also provides detailed information on the conservation status of D. hatagirea and strategies to overcome the exploitation of this orchid.

Epiphytism has evolved repeatedly in plants and has resulted in a considerable number of species with original characteristics. Because water supply is generally erratic compared to that in soils, succulent forms in particular are widespread in epiphytic species. However, succulent organs also exist in terrestrial plants, and the question of the concomitant evolution of epiphytism and succulence has received little attention, not even in the epidendroid orchids, which account for 67.6 % of vascular epiphytes.
We built a new time-calibrated phylogenetic tree of Epidendroideae with 203 genera treated in genus Orchidacearum, from which we reconstructed the evolution of epiphytism as well as traits related to water scarcity (stem and leaf succulence and the number of velamen layers), while testing for the correlated evolution between the two. Furthermore, we estimated the ancestral geographical ranges to evaluate the palaeoclimatic context in which epiphytism evolved.
Epiphytism evolved at least three times: 39.0 million years ago (Mya) in the common ancestor of the Malaxideae and Cymbidieae that probably ranged from the Neotropics to Southeast Asia and Australia, 11.5 Mya in the Arethuseae in Southeast Asia and Australia, and 7.1 Mya in the neotropical Sobralieae, and it was notably lost in the Malaxidiinae, Collabieae, Calypsoeae, Bletiinae and Eulophiinae. Stem succulence is inferred to have evolved once, in a terrestrial ancestor at least 4.1 Mya before the emergence of epiphytic lineages. If lost, stem succulence was almost systematically replaced by leaf succulence in epiphytic lineages.
Epiphytism may have evolved in seasonally dry forests during the Eocene climatic cooling, among stem-succulent terrestrial orchids. Our results suggest that the emergence of stem succulence in early epidendroids was a key innovation in the evolution of epiphytism, facilitating the colonization of epiphytic environments that later led to the greatest diversification of epiphytic orchids.

Bletilla striata is a well-known medicinal plant with high pharmaceutical and ornamental values. Polysaccharide is the most important bioactive ingredient in B. striata and has various health benefits. Recently, B. striata polysaccharides (BSPs) have attracted much attention from industries and researchers due to their remarkable immunomodulatory, antioxidant, anti-cancer, hemostatic, anti-inflammatory, anti-microbial, gastroprotective, and liver protective effects. Despite the successful isolation and characterization of BSPs, there is still limited knowledge regarding their structure-activity relationships (SARs), safety concerns, and applications, which hinders their full utilization and development. Herein, we provided an overview of the extraction, purification, and structural features, as well as the effects of different influencing factors on the components and structures of BSPs. We also highlighted and summarized the diversity of chemistry and structure, specificity of biological activity, and SARs of BSP. The challenges and opportunities of BSPs in the food, pharmaceutical, and cosmeceutical fields are discussed, and the potential development and future study direction are scrutinized. This article provides comprehensive knowledge and underpinnings for further research and application of BSPs as therapeutic agents and multifunctional biomaterials.

Anoectochilus roxburghii (Wall.) Lindl. (A. roxburghii), a valuable herbal medicine in China, has great medicinal and edible value. Polysaccharides, as one of the main active components of A. roxburghii, comprise glucose, arabinose, xylose, galactose, rhamnose, and mannose in different molar ratios and glycosidic bond types. By varying the sources and extraction methods of A. roxburghii polysaccharides (ARPS), different structural characteristics and pharmacological activities can be elucidated. ARPS has been reported to exhibit antidiabetic, hepatoprotective, anti-inflammatory, antioxidant, antitumor, and immune regulation activities. This review summarizes the available literature on the extraction and purification methods, structural features, biological activities, and applications of ARPS. The shortcomings of the current research and potential focus in future studies are also highlighted. This review provides systematic and current information on ARPS to promote their further exploitation and application.

BACKGROUND: Gymnadenia conopsea, a perennial herbaceous flowering plant that belongs to the family of Orchidaceae, sporadic distributed in the altitudes of 200-4700 m across northern Europe and, temperate and subtropical Asia region. The dried tubers of G. conopsea have been used to treat cough, asthma, and their syndromes, and also as a tonic in China and surrounding countries for a long history. G. conopsea is often processed deeply processed before use to enhance its efficacy. In recent years, because of its remarkable pharmacological activity and health care function, G. conopsea has been used more and more widely. Due to its extensive application and bad growth environment, the wild distribution of G. conopsea is decreasing and it has been listed as an endangered plant.
OBJECTIVE: This review aims to summarize the propagation and breeding, traditional uses, chemical composition, pharmacology, quality control, and processing of G. conopsea. Moreover, it also provides suggestions for the future high-value utilization of G. conopsea.
METHODS: A literature search on Gymnadenia genus and G. conopsea was performed using scientific databases including SciFinder, ACS, Web of Science, Springer, ScienceDirect, PubMed, and CNKI. Information was also collected from classic books of Chinese herbal medicine, official websites, Ph.D. and M.Sc. Dissertations, and so on. Structures of chemical compounds were drawn by ChemDraw software.
RESULTS: As of submission date of this manuscript, total 170 natural compounds have been isolated and characterized from G. conopsea, and all of the compounds were isolated from the tubers. The isolated compounds including benzylester glucosides, dihydrostilbenes, phenanthrenes, phenolic compounds, alkaloids, polysaccharide, lignans, flavones, triterpenoids, steroids, and other compounds. Some of these compounds and active extracts exhibited a wide range of pharmacological activities, in which, the tonifying, anti-fatigue, anti-oxidant, anti-viral, sedative and hypnotic activities are consistent with the traditional uses for the treatment of diseases. In addition, a variety of new pharmacological activities, such as preventing and treating gastric ulcers, immunoregulatory, anti-hyperlipidemia, anti-anaphylaxis, anti-silicosis, anti-cancer and neuroprotective activities have also been reported. However, the bioactive compounds responsible for most of the above pharmacological effects have not been well summarised till now. In this manuscript, analysis, speculation and summary of compounds that responsible for pharmacological effects were conducted.
CONCLUSIONS: The chemical constituents and pharmacological activities studies of G. conopsea extract have been summarised in this context, the isolated compounds responsible for the pharmacological activities were also analyzed and deduced according to the publications, all above led to suggestions for the future high-value utilization of G. conopsea.

Orchids are widely used in traditional medicine for the treatment of a whole range of different health conditions, and representatives of the Neotropical subtribe Maxillariinae are not an exception. They are utilized, for instance, for their spasmolytic and anti-inflammatory activities. In this work, we analyze the literature concerning the chemical composition of the plant extracts and secretions of this subtribe\'s representatives published between 1991 and 2022. Maxillariinae is one of the biggest taxa within the orchid family; however, to date, only 19 species have been investigated in this regard and, as we report, they produce 62 semiochemicals of medical potential. The presented review is the first summary of biologically active compounds found in Maxillariinae.