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Orchid Conservation and Associated Fungal Diversity

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A special issue of Diversity (ISSN 1424-2818). This special issue belongs to the section "Biodiversity Conservation".

Deadline for manuscript submissions: closed (20 February 2023) | Viewed by 11780

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Dr. Alžběta Novotná

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Guest Editor

Institute of Microbiology of the CAS, Vídeňská 1083, 142 20 Prague, Czech Republic
Interests: orchid mycorrhiza; fungal enzymes

Special Issue Information

Dear Colleagues,

Orchidaceae is one of the largest plant families on the planet, with approximately 28,500 accepted species. They are distributed in every continent except Antarctica, with the highest diversity present in the neotropical rainforests. In the tropics, Orchidaceae mainly occur as epiphytes, whereas in temperate regions they thrive as terrestrial plants or lithophytes. Despite the great species richness, orchids are some of the most threatened plants in the wild due to climate change, rapid habitat loss and illegal overcollection. The fragile beauty of orchid flowers has fascinated collectors, horticulturalists and orchid enthusiasts for centuries, contributing to their extinction in their natural habitats. Further, orchids are illegally overharvested for pharmaceutical and food industry use.

Despite the increasing horticultural and research interest, much remains to be understood about orchids; some part of this might be due to their intimate relationships with pollinators and mycorrhizal fungi. Orchids are mostly pollinated by insects and birds; some species use a broad range of pollinators, while others have flowers exquisitely adapted to a specific pollinator. Moreover, “smart” orchids widely use tricky pollination strategies such as sexual and food deception. Orchids have also developed an intimate relationship with mycorrhizal fungi. Widely spread fungal mycelia supply poorly developed orchid roots with inorganic soil nutrients as a reward for sugar uptake from the photosynthetic shoot. Tiny, dust-like orchid seeds would not be able to start germination without considerable food support from a proper mycorrhizal partner.

This Special Issue aims to summarize the latest knowledge in orchid science and the importance of orchids in understanding the sustainability of fragile environments. We welcome researchers in ecology, biotechnology, molecular biology, mycorrhizal associations, pollination strategies, taxonomy etc. to share their scientific results. Orchids deserve attention and research efforts from the scientific community. Data-driven and theoretical research are needed to further protect these unique jewels of Nature and preserve them for future generations.

Dr. Alžběta Novotná
Guest Editor

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Keywords

endangered species
mycorrhizal association
pollination strategies
Orchidaceae
orchid research

Published Papers (6 papers)

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Research

18 pages, 3093 KiB

Open AccessArticle

Community Richness and Diversity of Endophytic Fungi Associated with the Orchid Guarianthe skinneri Infested with “Black Blotch” in the Soconusco Region, Chiapas, Mexico

by Fabiola Hernández-Ramírez, Anne Damon, Sylvia Patricia Fernández Pavía, Karina Guillén-Navarro, Leobardo Iracheta-Donjuan, Eugenia Zarza and Ricardo Alberto Castro-Chan

Diversity 2023, 15(7), 807; https://doi.org/10.3390/d15070807 - 26 Jun 2023

Cited by 3 | Viewed by 1350

Abstract

Orchids coexist with a diversity of endophytic fungi within their roots and other parts of the plant. These are presumed to contribute to nutrition, and may protect the plants against pathogens and herbivores; however, some may be latent pathogens and/or bring no benefit to the plant. Guarianthe skinneri is an epiphytic Central American threatened orchid used as an ornamental plant and in the rituals and celebrations of many communities. However, in the Soconusco region (Chiapas, Mexico), the pseudobulbs of mature plants are affected by the Lasiodiplodia theobromae fungus, causing the disease “black blotch”. We evaluated and compared the diversity of the endophytic fungal community within the leaves, pseudobulbs and roots of mature plants in two conditions, asymptomatic and symptomatic. Thirty samples from each condition and tissue were amplified with ITS and sequenced by Illumina MiSeq. Sequences were obtained and analyzed to determine taxonomic assignment and functionality with FUNGuild, obtaining 1857 amplicon sequence variants (ASVs). Alpha diversity was similar between plant conditions. In symptomatic plants, significant differences were found between the three types of tissue. According to the FUNGuild functionality analysis, 368 ASVs were determined to be endophytic fungi. The tissues of G. skinneri plants are reservoirs of fungal endophytes that should be considered for further exploration for research and conservation purposes. Full article

(This article belongs to the Special Issue Orchid Conservation and Associated Fungal Diversity)

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20 pages, 4931 KiB

Open AccessArticle

In Vitro Seed Germination and Seedling Development of Dracula felix (Luer) Luer—An Orchid Native to Ecuador

by Paulina H. Quijia-Lamiña, Luis E. Baquero, Michael E. Kane and Lawrence W. Zettler

Diversity 2023, 15(6), 732; https://doi.org/10.3390/d15060732 - 02 Jun 2023

Viewed by 1400

Abstract

Effects of daily temperature fluctuations that mimic on-site environmental conditions were tested on seed germination and development in Dracula felix, a native epiphytic orchid from the neotropics. Mature seeds collected from a native population lost their viability from 60% to 37.78% and 0% after 8 and 16 weeks., respectively, under 22 ± 2 °C. Seed viability was completely lost when seeds were maintained at −10 °C in the dark. Less than 50% germination was observed in D. felix seed across all treatments. Seed germinated regardless of the light or temperature treatment. However, significant improvement in germination was observed at 17/22 °C compared to constant temperature treatments. Early seedling development stages were observed only on 1/2XMS and VW media at 17 °C or 17 °C/22 °C under a 12 h light photoperiod. Neither germination nor seedling development were improved by any fungal strain tested using standard symbiotic germination protocols. Information obtained from this study is critical to ensure the ex-situ conservation of this and other rare Dracula species under current and future climate change scenarios. Full article

(This article belongs to the Special Issue Orchid Conservation and Associated Fungal Diversity)

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25 pages, 5603 KiB

Open AccessArticle

Vanilla planifolia Andrews (Orchidaceae): Labellum Variation and Potential Distribution in Hidalgo, Mexico

by Agustín Maceda, Adriana Delgado-Alvarado, Víctor M. Salazar-Rojas and B. Edgar Herrera-Cabrera

Diversity 2023, 15(5), 678; https://doi.org/10.3390/d15050678 - 18 May 2023

Cited by 3 | Viewed by 1598

Abstract

Vanilla planifolia is a species of commercial importance. However, vanilla presents gene erosion problems due to its clonal reproduction. In the Huasteca of Hidalgo, there is no information on vanilla populations. Therefore, the objectives of this study were to identify the current populations and the potential distribution of, and the morphological variation in, the labellum of V. planifolia in the Huasteca of Hidalgo. Twenty-two accessions were located and selected. Based on 21 environmental variables, the niche modeling of the potential distribution was carried out with the MaxEnt program; with the Jackknife test being used to identify the variables that contributed to the model. Flowers from 22 accessions were collected and the labellum of each flower was dissected. Subsequently, 64 morphological variables were obtained and various multivariate analyses were performed. The results showed three regions, defined by the highest to the lowest probability that V. planifolia was distributed. The precipitation of the driest month, altitude, and vegetation cover delimited the distribution. Five different morphotypes were distinguished, and the main differences were associated with the middle part of the labellum as well as the entrance of pollinators to the flower; therefore, the characterization of the labellum showed an infraspecific variation in V. planifolia in populations of the Huasteca of Hidalgo. Full article

(This article belongs to the Special Issue Orchid Conservation and Associated Fungal Diversity)

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13 pages, 23672 KiB

Open AccessArticle

Initial Population Analysis and Mycorrhizal Fungi of the Leafless Epiphytic Orchid, Campylocentrum pachyrrhizum, in Florida

by Adam R. Herdman, Ernesto B. Mújica, Mark W. Danaher, Lawrence W. Zettler, Kurt Schulz and Elizabeth Esselman

Diversity 2023, 15(4), 576; https://doi.org/10.3390/d15040576 - 19 Apr 2023

Viewed by 1422

Abstract

Campylocentrum pachyrrhizum Rchb.f. Rolfe, also known as the ribbon orchid, is native to southern Florida, the West Indies, and northern South America. In Florida, it is restricted to the Fakahatchee Strand and is currently state-listed as endangered, but virtually nothing is known about the orchid’s biology, ecology, and current status. The purpose of this study was to document ribbon orchid populations within the northern portion of the Fakahatchee Strand (Florida Panther NWR) and to identify some of the biotic and abiotic factors critical to its survival. During 2016–2022, a total of 118 ribbon orchids were recorded at five sites on 21 host trees comprising two species (Annona glabra, Fraxinus caroliniana). The majority (80%) were rooted on pop ash, and over half (54%) were rooted at the base of trees 100–150 cm above the high water mark. The number of orchids decreased from year to year, with the largest drop (2017–2018) coinciding with damage from Hurricane Irma. At the end of the 2022 survey, only 44 orchids remained. Mycorrhizal fungi isolated from two plants were identified as a Ceratobasidium species. We urge land managers to take immediate action to safeguard this species throughout southern Florida. Full article

(This article belongs to the Special Issue Orchid Conservation and Associated Fungal Diversity)

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18 pages, 3797 KiB

Open AccessArticle

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

by Paulina H. Quijia-Lamiña, Luis E. Baquero, Michael E. Kane and Lawrence W. Zettler

Diversity 2023, 15(2), 236; https://doi.org/10.3390/d15020236 - 08 Feb 2023

Cited by 1 | Viewed by 2008

Abstract

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. Full article

(This article belongs to the Special Issue Orchid Conservation and Associated Fungal Diversity)

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23 pages, 2913 KiB

Open AccessArticle

Large-Scale In Vitro Multiplication and Phytochemical Analysis of Himantoglossum affine (Boiss.) Schltr.: An Endangered Euro-Mediterranean Terrestrial Orchid

by Mozhgan Fatahi, Yavar Vafaee, Nawroz Abdul-razzak Tahir and Jalal Khorshidi

Diversity 2022, 14(12), 1137; https://doi.org/10.3390/d14121137 - 18 Dec 2022

Cited by 2 | Viewed by 2218

Abstract

Himantoglossum affine is a threatened terrestrial orchid. We aimed to optimize asymbiotic seed germination and direct embryogenesis and to analyze the phytochemical profile and physico-biochemical analysis of leaf and tuber. The individual use of organic nitrogen compounds resulted in higher germination efficiencies, while the shortest times to germination were observed using coconut water plus casein hydrolysate. Plantlets grown on media supplemented with pineapple juice and peptone had the highest plantlet length and weight. For embryogenesis, the highest regeneration rate (44%) and embryo number/explant (10.12 ± 2.08) were observed in young protocorm-like body (PLB) explants with 0.5 mg/L naphthalene acetic acid (NAA) and 1 mg/L thidiazuron (TDZ). During the acclimatization process, the scattered vascular tubes converted to fully developed vascular tissues, ensuring maximum sap flux. Gas chromatography–mass spectrometry analysis identified 1,2,3-propanetriol, monoacetate, 4H-pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl, and 2-butenedioic acid, 2-methyl-, (E)- as the most prevalent compounds. We reported higher contents of total phenolics and flavonoids and antioxidant activity compared to other terrestrial orchids. The glucomannan content (36.96%) was also higher than starch content (31.31%), comparable to those reported in other tuberous orchids. Based on the fragmentation of H. affine populations in the Middle East and Euro-Mediterranean countries due to over-harvesting, climate change, and/or human impact, our procedure offers a tool for the re-introduction of in vitro-raised plants to threatened areas. Full article

(This article belongs to the Special Issue Orchid Conservation and Associated Fungal Diversity)

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