Orchid Research Articles

Epiphytic Orchids in the Flora of Ecuador: a Review of Their Richness, Abundance, Ethnobotanical Importance, and Conservation Strategies in the Context of the Sustainable Development Goals SDGs

Objective: The objective of this study is to describe the current status of the Orchidaceae family with respect to its conservation in the Canton Lago Agrio. Determine the richness and abundance of orchids in the Canton Lago Agrio. 2. Determine the ethnobotanical importance of the orchids of the Canton Lago Agrio. 3. To establish conservation strategies for the most representative orchids of the Lago Agrio Canton. Method: The methodology adopted for the research included field trips through direct and random observation, the use of taxonomic identification guides, an exhaustive bibliographic search in high impact databases such as Scopus and Web of Science, and the application of expert judgment. Results and Discussion: The results revealed the richness and abundance of orchids within the Lago Agrio canton. 42 species and 497 individuals, each of them with epiphytic habit. The importance of this taxonomic group lies in economic factors, such as, commercialization of specimens, use in medicine and gastronomic taste. Its main conservation strategies are environmental education and the implementation of informative posters in educational centers and natural spaces, such as natural parks. Research Implications: The results of this study have implications for orchid planning and conservation in Lago Agrio Canton. The research underscores the need for a multidisciplinary approach to taxonomic conceptualization and conservation, as well as the importance of considering the landscape as a central element in the development of sustainable tourism products and experiences. Originality/Value: This study contributes to the literature by providing a comprehensive and up-to-date review of the relationship between the natural landscape and orchid conservation status, bringing together knowledge from various disciplines.

Novel indicator film incorporating Dendrobium orchid extract and TiO2 nanoparticles for seafood freshness monitoring

This study aimed to develop a pH indicator film using a combination of hydrocolloids (polyvinyl alcohol, carboxymethyl cellulose, and rice flour; PCR film), Dendrobium orchid flower (DOF) extract, and TiO2 nanoparticles to monitor shrimp and crab freshness during 9 days of cold storage. LC-MS/MS analysis identified a rare anthocyanin, cyanidin-3-[6-sinapoyl-2-O-(2-(sinapoyl)glucosyl)-glucoside], in the DOF extract, responsible for its color expression. The DOF extract showed a clear color variation in different solutions (pH 1–13). TiO2 nanoparticles influenced the film's thickness, tensile strength (TS), elongation at break (EB), water vapor permeability (WVP), and color properties. Structural changes due to nanoparticles were confirmed via Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. PCR+DOF+8%TiO2 film showed the highest TS (13.75 ± 0.60 MPa), EB (2.24 ± 1.42 %), and WVP (3.57 ± 1.12 × 10-11 g·m·Pa-1·m-2·s-1) values and was more sensitive to ammonia vapor than acetic acid vapor. In practical applications, the film could effectively indicate shrimp spoilage through color change but was less precise for crab samples. The film effectively indicated shrimp spoilage through a color shift to green on the 4th day, correlating with total viable count and volatile nitrogen levels exceeding safe consumption thresholds. Thus, this film could serve as an efficient diagnostic tool for monitoring seafood spoilage.

Genomic, transcriptomic, and metabolomic analyses reveal convergent evolution of oxime biosynthesis in Darwin's orchid.

Angraecum sesquipedale, also known as Darwin's orchid, possesses an exceptionally long nectar spur. Charles Darwin predicted the orchid to be pollinated by a hawkmoth with a correspondingly long proboscis, later identified as Xanthopan praedicta. In this plant-pollinator interaction, the A. sesquipedale flower emits a complex blend of scent compounds dominated by diurnally regulated oximes (R1R2C=N-OH) to attract crepuscular and nocturnal pollinators. The molecular mechanism of oxime biosynthesis remains unclear in orchids. Here, we present the chromosome-level genome of A. sesquipedale. The haploid genome size is 2.10 Gb and represents 19 pseudochromosomes. Cytochrome P450 encoding genes of the CYP79 family known to be involved in oxime biosynthesis in seed plants are not present in the A. sesquipedale genome nor in the genomes of other members of the orchid family. Metabolomic analysis of the A. sesquipedale flower revealed a substantial release of oximes at dusk during the blooming stage. By integrating metabolomic and transcriptomic correlation approaches, flavin-containing monooxygenases (FMOs) encoded by six tandem-repeat genes in the A. sesquipedale genome are identified as catalyzing the formation of oximes present. Further in vitro and in vivo assays confirm the function of FMOs in the oxime biosynthesis. We designate these FMOs as Orchid Oxime Synthases 1-6. The evolutionary aspects related to the CYP79 gene losses and neofunctionalization of FMO-catalyzed biosynthesis of oximes in Darwin's orchid provide new insights into the convergent evolution of biosynthetic pathways.

Immunolocalization of Extensin and Pectin Epitopes in Liparis loeselii Protocorm and Protocorm-like Bodies.

Liparis loeselii (L.) Rich, an endangered member of the Orchidaceae family, is found in alkaline fens. With the declining populations of L. loeselii, there is a pressing need to reintroduce this species in Central Europe. As in vitro germination is a crucial tool for obtaining plants for introduction into the environment, we looked at the morphological changes occurring during the early stages of L. loeselii development in vitro. As the early stages of orchid development, especially the protocorm stage, are thought to be responsible for SAM formation and the initiation of symbiotic association, we focused on cell wall elements whose epitopes have been found in similar processes in other species: the extensin and pectin rhamnogalacturonan I (RG-I) side chain epitopes. We addressed the following questions: Does the cell wall of L. loeselii change its composition during the early stages of development, as noted in other species? Are there noticeable similarities in the cell wall to organs of different species whose function is to contact microorganisms? Are there regularities that allow the recognition of individual structures on this basis? Immunolocalization revealed changes in the distribution of certain extensins (JIM11 and JIM20) and RG-I (LM5 and LM6) side chain epitopes. Extensins, a type of cell wall protein, were observed during the initial stages of the formation of PLB and the shoot apical meristem of protocorms and PLBs. RG-I, on the other hand, was found to play a significant role in the development of the protocorm and PLB. In pseudobulbs, which appeared on the protocorms, extensins occurred in their storage part. However, RG-I side chains (1→4)-β-galactans (LM5), and (1→5)-α-L-arabinans (LM6) were not found in pseudobulbs. We revealed that a common feature of protocorms and PLBs was an increased amount of extensins, which were detected with the JIM11 antibody, and pectins, which were detected with the LM5 antibody, that were present together, which may prove helpful in determining the identity of the induced structures and distinguishing them from pseudobulbs. Thus, our study unveiled the role of extensins and RG-I during the growth of protocorms and PLBs. We suggest that PLBs may mimic the wall remodelling that occurs in protocorms, which indicates that using cell wall components is an invitation to be colonised by a fungal partner. However, this needs to be tested in future research. The findings of this research can help interpret future studies on the propagation, acclimatisation, and introduction of L. loeselii into the natural environment.

Understanding the Systematic Implications of Pollinium Morphology in the Aeridinae Subtribe (Orchidaceae)

Abstract— Molecular phylogenetic studies have been the basis for major clades proposed for the Aeridinae subtribe of the Orchidaceae family. However, systematic morphological characterization has yet to be conducted. We carried out this study on Aeridinae pollinium morphologies with an emphasis on aperture type and pollinium sculpturing to determine the systematic significance of these characteristics in the context of molecular phylogenetics. The results indicated that most Aeridinae species have cleft type pollinium apertures and that few have porate type or no aperture. The shapes of most of the pollinia were flat but this was not consistent at the genus level. Pollinium length ranged from 204 to 2606 µm, and the width from 178 to 1524 µm. Long and wide pollinia were commonly found in primitive groups, while short and narrow pollinia were commonly found in evolutionarily derived groups. The shapes and sizes of the individual units of the pollinia varied from uniform to variable, with a few exceptions. The individual units of most the pollinia were tetrads, and individual pollen grains were easily distinguished within the tetrad. The degree to which individual pollen grains could be differentiated is constant at the clade level except for Aerides rosea. The exine sculpturing characteristics were consistent in each clade except in the Cleisostoma and Phalaenopsis clades. The pollinium sculpturing has a somewhat clear pattern of change that was consistent with the molecular phylogeny, with a few exceptions. In conclusion, these pollinium characteristics themselves are not systematic, but they can serve as useful characteristics for determining the major systematic groups in the subtribe Aeridinae.

Molecular docking and in silico analysis of the pharmacokinetics, toxicological profile and differential gene expression of bioactive compounds from Cyrtopodium glutiniferum

The genus Cyrtopodium, from the Orchidaceae family, is widely used for its therapeutic properties in the treatment of tuberculosis, abscesses, urinary infection, and colds. C. glutiniferum, one of the species of this genus, is endemic in Brazil and largely used in herbal medicine. Thus, it is of great interest to recognize its composition, the properties of the molecules found in it. This study aimed to perform the in silico analysis of the main compounds from C. glutiniferum, on the platforms pKCSM, SwissADME, LAZAR, CLC-pred, ToxTree, DIGEPred, STRING, and Cytoscape. Further than this, the molecular docking was performed. The compounds present in the aqueous extract of C. glutiniferum were identified by UHPLC-MS/MS, finding Arbutin, Caffeic acid 4-O-glucoside, and Dihydroformononetin as the three most abundant molecules. The evaluation of the gastrointestinal absorption of Dihydroformononetin is given as high, also managing to cross the blood-brain barrier, while Arbutin can only be absorbed by the gastrointestinal tract and Caffeic acid 4-O-glucoside had very low absorption. Further analysis showed that Arbutin and Dihydroformononetin are possible leading molecules for drug synthesis, according to the prediction. Toxicological aspects were analysed, and no adverse effects were noted, but there were divergences in the mutagenic prediction of Arbutin and Dihydroformononetin, having different results in the used platforms, demonstrating that a cautious analysis and data insertion is needed in these tools to optimize them. The analysis of the differentially expressed genes predicted that the compounds can regulate several genes, including some genes associated with carcinogenesis and inflammation. The Molecular docking analysis showed high binding affinities of the molecules with different proteins. Therefore, C. glutiniferum demonstrates the potential to be used as a phytotherapeutic. The same was given through the in silico analysis of the three compounds found in the orchid, that show good individual potential.

Comparison of Orchid Conservation Between China and Other Countries

Global attention is highly focused on biodiversity conservation. Various countries are actively implementing relevant conservation measures. To advance these efforts in China, it is essential to understand global conservation actions. The orchid family, one of the most diverse groups of flowering plants, has become a “flagship” group for plant conservation. In this study, we summarized 3418 policies and regulations related to orchid conservation in 45 countries. We found that orchid conservation actions in various countries have focused on in situ conservation, with 1469 policies and regulations issued for nature reserves, while ex situ conservation has been seriously neglected, with only seven relevant regulations. Most developing countries have experienced an increase in orchid conservation actions, while developed countries have plateaued. We amassed 370 non-governmental organizations (NGOs) for orchid conservation. At present, the total number of policies and regulations for orchid protection in China is approximately 84, with 67 issued since 2000. Two non-governmental organizations have been established for orchid conservation. Although the benefit of orchid conservation in China is significant, it still requires continuous improvement compared to many other countries. We recommend that the Chinese government draws on the experiences of the United States, Canada, and Australia in areas such as policy and regulation formulation, optimization of non-governmental organizations, and implementation of related conservation projects. Through learning and collaboration, challenges can be transformed into opportunities for development.

Cremastrae Pseudobulbus Pleiones Pseudobulbus (CPPP) Against Non-Small-Cell Lung Cancer: Elucidating Effective Ingredients and Mechanism of Action.

Cremastrae Pseudobulbus Pleiones Pseudobulbus (CPPP) is derived from the dried pseudobulb of the orchid family plants Cremastra appendiculata (D.Don) Makino, Pleione bulbocodioides (Franch.) Rolfe, or Pleione yunnanensis Rolfe, and has the properties of clearing heat, detoxification, resolving phlegm, and dispersing nodules. It is frequently used for the treatment of various malignant tumors in clinical practice, especially lung cancer. CPPP is divided into two commercial specifications in the market, Maocigu (MCG) and Bingqiuzi (BQZ). However, owing to a lack of appropriate research strategies, the active ingredients and molecular mechanisms involved have not yet been clarified. This study intended to discover the combination of effective anti-lung-cancer ingredients in CPPP and explore their potential mechanisms of action. In this study, UHPLC-MS fingerprints of MCG and BQZ were established separately. Inhibitory effects on the proliferative viability and migratory ability of A459 and H1299 cells were evaluated as pharmacodynamic indicators. GRA and BCA were used to determine spectrum-effect relationships. Next, the identification and analysis of components of drug-containing serum were performed using UHPLC-Q-Exactive Orbitrap MS. Then, the results of the two analyses were combined to jointly screen out the anti-lung-cancer candidate active monomers of CPPP, and their in vitro activities were verified. Afterward, all effective ingredient combinations of MCG (MCGC) and BQZ (BQZC) were prepared according to their contents in the original medicinal materials. Their anti-lung-cancer activities in vitro and in vivo were compared and verified. Finally, we used the human lung cancer cell line A549 and the Lewis tumor xenograft model to investigate how BQZC would influence autophagy and apoptosis processes and the mechanisms involved. Overall, 11 predominant anti-lung-cancer active ingredients from CPPP were screened. Next, MCGC and BQZC were prepared according to their contents in the original medicinal materials, respectively, and their anti-tumor effects were equivalent to those of the original materials in vitro and in vivo. We found that BQZC could inhibit lung cancer cell growth and induce protective autophagy and apoptosis in lung cancer cells by activating the AMPK-mTOR-ULK1/BMF signaling pathway. These results provide important evidence for the clinical application and deep development of CPPP against tumors.

Comparison of the chloroplast genomics of nine endangered Habenaria species and phylogenetic analysis

BackgroundHabenaria, a genus in the family Orchidaceae, are the nearly cosmopolitan orchids, and most species have significant medicinal and ornamental values. Despite the morphological and molecular data that have been studied in recent years, the phylogenetic relationship is still unclear.ResultsWe sequenced, assembled, and annotated the chloroplast (cp) genomes of two species (Habenaria aitchisonii Rchb.f. and Habenaria tibetica Schltr.ex Limpricht) of Habenaria grown on the Qinghai-Tibetan Plateau (QTP), and compared them with seven previously published cp genomes which may aid in the genomic profiling of these species. The two genomes ranged from 155,259–155,269 bp in length and both included 132 genes, encoding 86 proteins, 38 tRNAs and 8 rRNAs. In the cp genomes, the tandem repeats (797), SSRs (2195) and diverse loci (3214) were identified. Comparative analyses of codon usage, amino frequency, microsatellite, oligo repeats and transition and transversion substitutions revealed similarities between the species. Moreover, we identified 16 highly polymorphic regions with a nucleotide diversity above 0.02, which may be suitable for robust authentic barcoding and inferring in the phylogeny of Habenaria species. Among the polymorphic regions, positive selection was significantly exerted on several genes, such as cemA, petA, and ycf1. This finding may suggest an important adaptation strategy for the two Habenaria species on the QTP. The phylogenetic relationship revealed that H. aitchisonii and H. tibetica were more closely related to each other than to the other species, and the other seven species were clustered in three groups. In addition, the estimated divergence time suggested that the two species separated from the others approximately 0.39 Mya in the Neogene period. Our findings also suggest that Habenaria can be divided into different sections.ConclusionsThe results of this study enriched the genomics resources of Habenaria, and SSR marker may aid in the conservation management of two endangered species.

Exploring the medicinal potential of Dendrobium: Uncovering the spatial distribution of flavonoids and alkaloids in 15 species of Dendrobium using MALDI-MSI

Dendrobium, the second largest genus in the Orchidaceae family, has been regarded as a valuable medicinal plant throughout Chinese history. Secondary metabolites present in the stem of Dendrobium, including alkaloids and flavonoids, confer significant pharmacological effects such as anti-inflammatory, antibacterial, immunomodulatory, antitumor, and antioxidant properties. To our knowledge, this study is the first to apply matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) technology to comprehensively identify the spatial distribution of secondary metabolites, particularly flavonoids and alkaloids, in the mature stems of 15 common Dendrobium species. By analyzing the matching scores and relative concentrations of compounds, 20 flavonoids and 19 alkaloids with high identification credibility were identified, along with 4 sesquiterpenoid compounds. Their spatial distributions and compositions were analyzed, and the results revealed that despite the similar structural basis of the stems in the 15 Dendrobium species, significant differences existed in the distribution of secondary metabolites among different species. Flavonoids and alkaloids with different medicinal effects exhibited certain specific distribution patterns; for instance, flavonoids with antioxidant effects were mostly concentrated in the outer circle of thin-walled cells of Dendrobium stems, whereas those with antitumor effects were found in higher concentrations in the central areas of some Dendrobium species than in the periphery. Alkaloids with antitumor properties typically exhibited a higher concentration in peripheral thin-walled cells than in central regions. Furthermore, statistical analysis was conducted on the content of secondary metabolites with different effects among the 15 Dendrobium species to identify species with greater medicinal potential in terms of antioxidant and antitumor effects. The findings of this study not only enhance our understanding of the distribution patterns of flavonoids and alkaloids within Dendrobium stems but also offer valuable insights for the medicinal development and quality assessment of Dendrobium.

Pollinator diversity of the food-deceptive orchids in southern Italy.

The orchid family is renowned for its enormous diversity in pollination biology. Many orchid species use deception to attract pollinators, and the main strategy in terrestrial orchids is food deception. Food-deceptive orchids usually show a low number of pollinator visitations, making field observations of pollinators difficult. In this study visual census, pollinator capture and molecular analysis of pollinaria found on caught insects allowed us to obtain information on species composition of orchid pollinators. A total of 321 insects were caught; most specimens were hymenopterans (Apis mellifera, Bombus ruderatus and Eucera rufa) and coleopterans (Tropinota hirta and T. squalida). The identity of species to which pollinaria found on the insect's body belonged was confirmed by molecular analysis. Moreover, some individuals of Billaea lata (Tachinidae, Diptera) were captured and photographed with the pollinaria on their head. Two new and important results emerged clearly in this work: a dipteran, Billaea lata, pollinator of Anacamptis pyramidalis, and two beetles in the genus Tropinota are pollinators of Orchis italica. Our results confirm that generalized food-deceptive orchids of the genera Orchis and Anacamptis show weak pollinator specificity.

Properties Characterization and Identification of Saponarin and Ribosnarin (apigenin-6-C-ribosyl -7-O-glucoside) Extracted Abundantly from the White-Color Moth Orchid Flowers (Phalaenopsis Hybrids)

Properties Characterization and Identification of Saponarin and Ribosnarin (apigenin-6-C-ribosyl -7-O-glucoside) Extracted Abundantly from the White-Color Moth Orchid Flowers (Phalaenopsis Hybrids)

Specialized seed dispersal in Neotropical Vanilla reveals fruit unpalatability to omnivores.

Flowering plants are essentially sessile organisms that disperse their genes through pollination, expanding their areas of occurrence through seed dispersal. In orchids, seed dispersal is commonly mediated by air currents. Conversely, members of several genera have evolved seeds adapted to endozoochory. This is the case for Vanilla, the most economically important genus in the orchid family. The role of indehiscent fruits in the attraction and rewarding of Vanilla seed dispersers was investigated based on field observations, analysis of fragrances, reward substances, and investigation of seed viability through the digestive tract. Indehiscent Vanilla fruits are consumed exclusively by herbivores, i.e. agoutis. Besides providing nutritional rewards, the fruits are rich in polyphenols that are unpalatable to omnivores. The most dominant compound in fruits is attractive only to agoutis. This is the first study showing synzoochory in Orchidaceae and specificity of seed dispersal in orchids. Indehiscent fruits may have evolved early in Neotropical Vanilla in response to selection pressures mediated by large herbivores as the genus emerged ca. 34 Mya in South America, concomitantly with megafauna diversification in the Oligocene. Extinction of the megafauna during the Pleistocene has left agoutis as inheritors of seed dispersal in species with large fleshy fruits. Apart from the effects on omnivores, this study shows that indehiscent fruits of V. chamissonis are consumed exclusively by agoutis, providing the first evidence of target mutualism in orchid seed dispersal.

Flowers meet Newton: testing the role of gravitational pull in resupination of orchid flowers.

Resupination refers to the developmental orientation changes of flowers through ≈180º, leaving them effectively upside-down. It is a widespread trait present in 14 angiosperm families, including the Orchidaceae, where it is a gravitropic phenomenon actively controlled by auxins. Here, we demonstrate that the passive gravitational pull on flower parts can have an additional influence on resupination. We studied a lady's slipper orchid in which some flowers naturally fail to resupinate. We conducted a manipulative experiment removing floral parts and showed that both the probability of complete resupination and the degree of flower vertical movement (from 0º - 180º) are related to the mass of floral organs. During flower development, the tip of the ovary slightly curves actively (14.75º) due to gravitropism. This promotes a lever arm effect so that the gravitational pull acting on flower mass creates a torque that bends the ovary, orienting the flower into a resupinate position that is accessible to pollinators. The role of the mass of floral organs in resupination provides new insights into flower development and its role in pollination mechanisms.

Characterization of the complete chloroplast genome of Liparis gigantea (Orchidaceae)

Liparis gigantea is a Chinese traditional medicinal herb in the Orchidaceae family. It is a rare and special Liparis species that exhibits relatively large flowers. To illuminate its phylogenetic status and augment genomic resources, the complete chloroplast (cp) genome of L. gigantea was first sequenced and assembled using whole genome next-generation sequencing in this study. The cp genome size is 158,462 bp with a total GC content of 36.9%. Characterized by a quadripartite structure, the genome consists of a large single-copy (LSC) region of 86,032 bp, a small single-copy (SSC) region of 18,322 bp, which is separated by a pair of 27,054 bp inverted repeat regions (IRs). A total of 133 genes were annotated, including 87 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. Phylogenetic analysis strongly supported L. gigantea as the sister to two closely related terrestrial species, Liparis nervosa and L. vivipara. The results of this study provide genomic information for future research and application of this medicinal herb.

Chemistry and Biotechnological Insights of Rhynchostylis retusa (L.) Blume: A Mini-Review

Abstract: Rhynchostylis retusa (L.) Blume belongs to the Vanda alliance of the Orchidaceae family and is mostly distributed from 300-1,500 m. It is traditionally practiced for the treatment of health issues such as dysentery, pain, inflammation, arthritis, and, skin, respiratory, heart, kidney, brain, and menstrual problems. R. retusa is also used in folklore claims to recover from tuberculosis, vertigo, anemia, and bone fractures. Further, some of the traditional claims were scientifically validated through preclinical (In vitro & in vivo) studies. With the view of tremendous health benefits, the current study was focused on harnessing the information through search engines (Google Scholar, Scopus-Elsevier, Medline, Sci Finder, Web of Science, Plant list, and Directory of Open Access Journal) till October 2022 and compile them as a comprehensive review. Therefore, detailed, comprehensive information on botanical distribution, ethnopharmacological and ornamental values, chemistry, biotechnological interventions for smart cultivation, pharmacological activities, conservation status, patents, and future perspectives of the R. retusa has been compiled. The comprehensive review of the Foxtail Orchid (R. retusa) has unremarkable potential and still needs to be explored from chemical, pharmacological, quality control, and value addition perspectives. The review will help the orchid community as well as researchers and farmers working on orchids.

Time to flowering of ornamental orchids

Objective: To analyze features of time to flowering of orchids and some strategies for its control in cultivation for ornamental purposes. Design/methodology/approach: Information from various authors and our own data is shown, in relation to the management of flowering time of ornamental orchids, based on treatments of environmental effects, plant growth regulators (PGRs) and nutrition. Findings/conclusions: It is possible to reduce the flowering time of orchids by environmental modifications, mainly temperature and photoperiod. This can also be achieved by nutritional management, mainly macro-nutritional, and through organic nutrition and PGRs. However, much more information is needed, especially for native orchid species with ornamental potential.

Complete chloroplast genome of a montane plant Spathoglottis aurea Lindl.: Comparative analyses and phylogenetic relationships among members of tribe collabieae.

The yellow-flowered Spathoglottis aurea (tribe Collabieae; family Orchidaceae) is native to the mountainous areas of Peninsular Malaysia. The species is well known as an ornamental plant and for its role in artificial hybrid breeding. There is an interesting evolutionary relationship between S. aurea and the geographically isolated S. microchilina from Borneo that has encouraged further study of the S. aurea populations, but the genomic resource for S. aurea has not yet been reported. The present study reports the first work to characterize a chloroplast (cp) genome among the Spathoglottis genus. The complete cp genome of S. aurea was assembled from a sequence generated by the Illumina platform and analysed in comparison with other Collabieae species available in the GenBank database. The cp genome of S. aurea is 157,957 base pairs (bp) in length with guanine-cytosine (GC) content of 37.3%. The genome possessed a typical quadripartite cp genome structure with large single-copy (LSC) (86,888 bp), small single-copy (SSC) (18,125 bp) and inverted repeat (IR) (26,472 bp) sequences. A total of 134 genes were annotated, with 88 protein coding genes (PCGs), 38 transfer RNA (tRNA) genes and eight ribosomal RNA (rRNA) genes. Overall, 80 simple sequence repeats (SSR) or microsatellites were identified. Comparative analysis with other Collabieae species revealed high conservation in the cp genome arrangements with minimal difference in genome lengths. However, several mutational hotspots were also detected, with high potential to be developed as genetic markers for phylogenetic analysis. Characterization of the S. aurea cp genome revealed its conserved nature without gene loss or rearrangements when compared to other species of the Collabieae tribe. Phylogenetic analysis of Collabieae species also revealed that S. aurea has a distant evolutionary relationship to other members of the Collabieae species, despite the presence of problematic genera such as Phaius and Cephalantheropsis.

Pollination ecology of Dracula erythrochaete (Orchidaceae): brood-site imitation or food deception?

Abstract Pleurothallidinae is the most diverse Neotropical subtribe in Orchidaceae and is almost exclusively pollinated by insects of the order Diptera. Dracula, a genus of 138 species in the Pleurothallidinae, is known to attract Zygothrica (Drosophilidae) flies, common macrofungi visitors, by imitating fungal volatile compounds and lamellae. Interestingly, Dracula orchids do not appear to offer any rewards to their floral visitors. While brood-site imitation of macrofungi has been suggested as their pollination system, the exact behaviour of flies during their extended visits to the orchid flowers has yet to be confirmed. In this study, we document the pollination mechanism of Dracula erythrochaete. We characterize the floral structures involved in the mechanism using anatomical and morphological evidence. Additionally, through in situ observations and camera recordings, we describe the insect behaviour. We show that flowers of D. erythrochaete share the same group of visitors as nearby macrofungi, including different Zygothrica species, seven of which were determined as effective pollinators. Male and female flies were attracted to the flowers and displayed feeding behaviour. Accordingly, proteins were detected in high concentrations on the papillae at the base of the movable lip and in papillary trichomes of the sepals, near the column. The concept of brood-site imitation is debated, as no oviposition events were observed and no eggs were found on the flowers. Therefore, a mixed strategy of congregation/brood-site imitation and food reward is proposed for pollination.

Analysis of Codon Usage Bias in the Plastid Genome of Diplandrorchis sinica (Orchidaceae).

In order to understand the bias and main affecting factors of codon usage in the plastid genome of Diplandrorchis sinica, which is a rare and endangered plant species in the Orchidaceae family, the complete plastid genome sequence of D. sinica was downloaded from the GenBank database and 20 protein-coding sequences that met the analysis requirements were finally selected. The GC content, length of the amino acid (Laa), relative synonymous codon usage (RSCU), and effective number of codon (ENC) of each gene and codon were calculated using the CodonW and EMBOSS online programs. Neutral plot analysis, ENC-plot analysis, PR2-plot analysis, and correspondence analysis were performed using Origin Pro 2024 software, and correlation analysis between various indicators was performed using SPSS 23.0 software. The results showed that the third base of the codon in the plastid genome of D. sinica was rich in A and T, with a GC3 content of 27%, which was lower than that of GC1 (45%) and GC2 (39%). The ENC value ranged from 35 to 57, with an average of 47. The codon usage bias was relatively low, and there was a significant positive correlation between ENC and GC3. There were a total of 32 codons with RSCU values greater than 1, of which 30 ended with either A or U. There were a total of nine optimal codons identified, namely, UCU, UCC, UCA, GCA, UUG, AUA, CGU, CGA, and GGU. This study indicated that the dominant factor affecting codon usage bias in the plastid genome of D. sinica was natural selection pressure, while the impact of base mutations was limited. The codon usage patterns were not closely related to gene types, and the distribution of photosynthetic system genes and ribosomal protein-coding gene loci was relatively scattered, indicating significant differences in the usage patterns of these gene codons. In addition, the codon usage patterns may not be related to whether the plant is a photosynthetic autotrophic or heterotrophic nutritional type. The results of this study could provide scientific references for the genomic evolution and phylogenetic research of plant species in the family Orchidaceae.