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Lee YI, Yeung EC. The orchid seed coat: a developmental and functional perspective. BOTANICAL STUDIES 2023; 64:27. [PMID: 37755558 PMCID: PMC10533777 DOI: 10.1186/s40529-023-00400-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 09/05/2023] [Indexed: 09/28/2023]
Abstract
Orchid seeds are 'dust-like.' The seed coat is usually thin, with only one to a few cell layers. It originates from the integuments formed during ovule development. In orchids, the outer integument is primarily responsible for forming a mature seed coat. The inner integument usually fails to develop after fertilization, becomes compressed, and collapses over the expanding embryo. Hence, the seed coat is formed from the funiculus, chalaza, and outer integumentary cells. The outermost layer of the seed coat, the testa, is lignified, usually at the radial and inner tangential walls. The subepidermal thin-walled layer(s), the tegmen, subsequently cold, resulting in seeds having only a single layer of seed coat cells. In some species, cells of the inner integument remain alive with the ability to synthesize and accumulate lipidic and or phenolic compounds in their walls covering the embryo. This cover is called the 'carapace,' a protective shield contributing to the embryo's added protection. A developmental and functional perspective of the integuments and seed coat during seed development and germination is presented in this review.
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Affiliation(s)
- Yung-I Lee
- Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan.
- Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, 10617, Taiwan.
| | - Edward C Yeung
- Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4, Canada.
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Rogo U, Fambrini M, Pugliesi C. Embryo Rescue in Plant Breeding. PLANTS (BASEL, SWITZERLAND) 2023; 12:3106. [PMID: 37687352 PMCID: PMC10489947 DOI: 10.3390/plants12173106] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/14/2023] [Accepted: 08/19/2023] [Indexed: 09/10/2023]
Abstract
Embryo rescue (ER) techniques are among the oldest and most successful in vitro tissue culture protocols used with plant species. ER refers to a series of methods that promote the development of an immature or lethal embryo into a viable plant. Intraspecific, interspecific, or intergeneric crosses allow the introgression of important alleles of agricultural interest from wild species, such as resistance or tolerance to abiotic and biotic stresses or morphological traits in crops. However, pre-zygotic and post-zygotic reproductive barriers often present challenges in achieving successful hybridization. Pre-zygotic barriers manifest as incompatibility reactions that hinder pollen germination, pollen tube growth, or penetration into the ovule occurring in various tissues, such as the stigma, style, or ovary. To overcome these barriers, several strategies are employed, including cut-style or graft-on-style techniques, the utilization of mixed pollen from distinct species, placenta pollination, and in vitro ovule pollination. On the other hand, post-zygotic barriers act at different tissues and stages ranging from early embryo development to the subsequent growth and reproduction of the offspring. Many crosses among different genera result in embryo abortion due to the failure of endosperm development. In such cases, ER techniques are needed to rescue these hybrids. ER holds great promise for not only facilitating successful crosses but also for obtaining haploids, doubled haploids, and manipulating the ploidy levels for chromosome engineering by monosomic and disomic addition as well substitution lines. Furthermore, ER can be used to shorten the reproductive cycle and for the propagation of rare plants. Additionally, it has been repeatedly used to study the stages of embryonic development, especially in embryo-lethal mutants. The most widely used ER procedure is the culture of immature embryos taken and placed directly on culture media. In certain cases, the in vitro culture of ovule, ovaries or placentas enables the successful development of young embryos from the zygote stage to maturity.
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Affiliation(s)
| | | | - Claudio Pugliesi
- Department of Agriculture Food and Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy; (U.R.); (M.F.)
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Šoch J, Šonka J, Ponert J. Acid scarification as a potent treatment for an in vitro germination of mature endozoochorous Vanilla planifolia seeds. BOTANICAL STUDIES 2023; 64:9. [PMID: 37067667 PMCID: PMC10110789 DOI: 10.1186/s40529-023-00374-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 04/03/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND Vanilla planifolia is the most widely cultivated species of vanilla with high economic importance. However, seed germination under artificial conditions is difficult and yields low germination percentages. The seeds are adapted to endozoochorous dispersal, and we therefore tried to simulate the conditions in the digestive tract by acid scarification of seeds. RESULTS Immature seeds lacking dormancy, used as a control, showed the highest germination percentage. Among the treatments tested for mature seeds, the hydrochloric acid treatments were significantly the best in breaking dormancy and inducing germination, irrespective of the acid concentration and the presence of pepsin. Conventional treatment with a hypochlorite solution induced much lower germination percentage. Sulphuric acid at concentration 50% was too strong and caused damage to the seeds. Important factor is also high cultivation temperature 30 °C as there was nearly no germination at 25 °C. CONCLUSIONS Our protocol significantly improves the efficiency of generative propagation of vanilla and allows for significantly higher germination percentages than previously described. The strongly positive effect of hydrochloric acid may be related to the adaptation of seeds to endozoochorous dispersal.
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Affiliation(s)
- Jan Šoch
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague, Czech Republic
| | - Josef Šonka
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague, Czech Republic
| | - Jan Ponert
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague, Czech Republic.
- Prague Botanical Garden, Trojská 800/196, 171 00, Prague, Czech Republic.
- Institute of Botany, Czech Academy of Sciences, 252 43, Průhonice, Czech Republic.
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Moreno-Camarena M, Ortega-Larrocea MP. Mesoamerican Cypripedium: Mycorrhizal Contributions to Promote Their Conservation as Critically Endangered Species. PLANTS (BASEL, SWITZERLAND) 2022; 11:1554. [PMID: 35736705 PMCID: PMC9227847 DOI: 10.3390/plants11121554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/28/2022] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
In the valuable orchid genus Cypripedium, the section Irapeana consists of a distinctive group of Mesoamerican species that is formed by Cypripedium dickinsonianum Hágsater, C. irapeanum Lex., and C. molle Lindl. All lady slipper orchids exhibit different distributions and abundances. Data analysis that used herbarium accessions and field investigations indicated that the habitats of these three species have been dramatically reduced. Prospecting for suitable habitats based on climatic, vegetation, and soil parameters allows us to predict potential distributions. Conservation strategies, such as ex situ propagation by asymbiotic and symbiotic approaches, have indicated that the culture media used are a determining factor for seedling development. Mycorrhizal isolates play a main role in the compatibility and further development of germinated seeds. The fungi isolated from adult plants belong to two different families, which makes it possible that widely distributed C. irapeanum populations will be fungal-specific as well as restricted for C. molle. Root mycorrhization patterns occur high on the secondary roots. In contrast with other species of the genus, in situ germination can occur over a short period of two months, but we have documented periods as long as ten years. Cypripedium is a highly problematic genus for ex situ conservation because the germination requirements and cultures are poorly documented, and there is great urgency for in situ conservation to develop strategies for identifying hotspot habitats and actualize the protection status to avoid extinction of this genus.
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Affiliation(s)
- Mauricio Moreno-Camarena
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico;
| | - María Pilar Ortega-Larrocea
- Departamento de Ciencias Ambientales y del Suelo, Instituto de Geología, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
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Pradhan N, Fan X, Martini F, Chen H, Liu H, Gao J, Goodale UM. Seed viability testing for research and conservation of epiphytic and terrestrial orchids. BOTANICAL STUDIES 2022; 63:3. [PMID: 35142915 PMCID: PMC8831675 DOI: 10.1186/s40529-022-00333-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 11/14/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Seed viability testing is essential in plant conservation and research. Seed viability testing determines the success of ex-situ conservation efforts, such as seed banking but commonly testing protocols of orchids lack consistency and accuracy, therefore, there is a need to select an appropriate and reliable viability test, especially when conducting comparative studies. Here, we evaluated the suitability of three seed viability tests, Evans blue test (EB), Fluorescein diacetate test (FDA) and Tetrazolium test (TTC), with and without sterilization, on seeds of 20 orchid species, which included five epiphytes and fifteen terrestrials, using both fresh seeds and seeds stored at - 18 ºC for 6 to 8 years. RESULTS We found that sterilization and lifeform of seeds affected seed viability across all tests but the storage time was not an influential factor. Sterilization negatively affected seed viability under EB and FDA test conditions but increased the detection of viable seeds in the TTC test in both epiphytic and terrestrial species. The EB test, when administered without sterilization provided the highest viability results. Being non-enzymatic unlike TTC and FDA tests, as expected, the EB test was the most reliable with similar results between sterilized and not sterilized seeds for most epiphytic and terrestrial species as well as when compared between groups. CONCLUSIONS The lifeform of the species and seed sterilization prior to testing are important influential factors in orchid seed viability testing. Since EB test was found to be reliable we recommend the EB test for seed viability assessment in orchids rather than the less reliable but commonly used TTC test, or the FDA test, which require more expensive and sophisticated instrumentation. Since storage time was not an influential factor in orchid seed viability testing, the recommendations of this study can be used for both fresh as well as long-term stored orchid seeds. This is helpful for research and especially for conservation measures such as seed banking. However, due to the species specificity of the bio-physiology of orchids, we call for comprehensive viability test assessment in the hyper diverse orchid family to be extended to a greater number of species to facilitate efficient conservation and research.
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Affiliation(s)
- Namrata Pradhan
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004 People’s Republic of China
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004 People’s Republic of China
- Seed Conservation Specialist Group, Species Survival Commission, International Union for Conservation of Nature (IUCN), 281196 Gland, Switzerland
| | - Xuli Fan
- Lab of Ecology and Evolutionary Biology, Chenggong Campus, Yunnan University, University Town, Chenggong New District, Kunming, Yunnan 650504 People’s Republic of China
| | - Francesco Martini
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004 People’s Republic of China
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004 People’s Republic of China
- Present Address: Faculty of Forest and Wood Sciences, Department of Forest Ecology, Czech University of Life Sciences Prague, Prague, Czech Republic
| | - Huayang Chen
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093 People’s Republic of China
| | - Hong Liu
- International Center for Tropical Botany, Department of Earth and Environment, Florida International University, 11200 SW 8th Street Miami, Florida, 33199 USA
| | - Jiangyun Gao
- Lab of Ecology and Evolutionary Biology, Chenggong Campus, Yunnan University, University Town, Chenggong New District, Kunming, Yunnan 650504 People’s Republic of China
| | - Uromi Manage Goodale
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004 People’s Republic of China
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Daxuedonglu 100, Nanning, Guangxi 530004 People’s Republic of China
- Seed Conservation Specialist Group, Species Survival Commission, International Union for Conservation of Nature (IUCN), 281196 Gland, Switzerland
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Gao Y, Ji J, Zhang Y, Yang N, Zhang M. Biochemical and transcriptomic analyses of the symbiotic interaction between Cremastra appendiculata and the mycorrhizal fungus Coprinellus disseminatus. BMC PLANT BIOLOGY 2022; 22:15. [PMID: 34983403 PMCID: PMC8725509 DOI: 10.1186/s12870-021-03388-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Cremastra appendiculata is a rare terrestrial orchid with a high market value as an ornamental and medicinal plant. However, the species depends entirely on fungi for seed germination under natural conditions. In a previous study, we have successfully isolated and identified the mycorrhizal fungus Coprinellus disseminatus which was able to induce the germination of C. appendiculata seeds. We then speculated that C. disseminatus may do so by breaking the testa imposed dormancy of the seeds. In this study, biochemical and transcriptomic analyses were used to characterize the germination of C. appendiculata seeds, collected at different stages of germination, as affected by C. disseminatus. RESULTS The lignocellulose in the seeds coat of C. appendiculata was degraded by the mycorrhizal fungus resulting in facilitated absorption of water. The rate of decline in lignin content was 67 and 73% at 6 and 12 days after sowing, respectively. The water content increased from 13 to 90% during symbiosis. A total of 15,382 genes showing significantly different levels of expression (log2 FPKM≥2.0, Qvalue≤0.05) were successfully identified among all libraries, where the highest number of DEGs was shared between 6 days versus 0 day after symbiotic germination. Gene annotation results suggested that 15 key genes related water-status, such as DHN gene family and Xero 1 were down-regulated. The genes zeaxanthin epoxidase ZEP, 9-cis-epoxycarotenoid dioxygenase NCED3 and β-carotene hydroxylase involved in the biosynthesis of abscisic acid (ABA) were significantly down-regulated in 6 days as compared to 0 day after symbiotic germination. CONCLUSIONS This work demonstrates that mycorrhizal fungus C. disseminatus can stimulate C. appendiculata seeds germination through a mechanism of breaking the testa imposed dormancy and inducing water absorption of the embryo.
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Affiliation(s)
- Yanyan Gao
- College of Life Sciences, Guizhou University, Guiyang, 550025, Guizhou, China
- Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guiyang, 550025, Guizhou, China
| | - Jun Ji
- College of Life Sciences, Guizhou University, Guiyang, 550025, Guizhou, China
- Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guiyang, 550025, Guizhou, China
| | - Yujin Zhang
- College of Life Sciences, Guizhou University, Guiyang, 550025, Guizhou, China
- Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guiyang, 550025, Guizhou, China
| | - Ningxian Yang
- College of Life Sciences, Guizhou University, Guiyang, 550025, Guizhou, China
- Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guiyang, 550025, Guizhou, China
| | - Mingsheng Zhang
- College of Life Sciences, Guizhou University, Guiyang, 550025, Guizhou, China.
- Key Laboratory of Plant Resources Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guiyang, 550025, Guizhou, China.
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Do compounds involved in plant resistance to fungal attack facilitate germination in the fully mycoheterotrophic orchid Cyrtosia septentrionalis? Symbiosis 2021. [DOI: 10.1007/s13199-021-00788-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Ren LY, Zhao H, Liu XL, Zong TK, Qiao M, Liu SY, Liu XY. Transcriptome Reveals Roles of Lignin-Modifying Enzymes and Abscisic Acid in the Symbiosis of Mycena and Gastrodia elata. Int J Mol Sci 2021; 22:6557. [PMID: 34207287 PMCID: PMC8235111 DOI: 10.3390/ijms22126557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/16/2021] [Accepted: 06/16/2021] [Indexed: 01/17/2023] Open
Abstract
Gastrodia elata is a well-known medicinal and heterotrophic orchid. Its germination, limited by the impermeability of seed coat lignin and inhibition by abscisic acid (ABA), is triggered by symbiosis with fungi such as Mycena spp. However, the molecular mechanisms of lignin degradation by Mycena and ABA biosynthesis and signaling in G. elata remain unclear. In order to gain insights into these two processes, this study analyzed the transcriptomes of these organisms during their dynamic symbiosis. Among the 25 lignin-modifying enzyme genes in Mycena, two ligninolytic class II peroxidases and two laccases were significantly upregulated, most likely enabling Mycena hyphae to break through the lignin seed coats of G. elata. Genes related to reduced virulence and loss of pathogenicity in Mycena accounted for more than half of annotated genes, presumably contributing to symbiosis. After coculture, upregulated genes outnumbered downregulated genes in G. elata seeds, suggesting slightly increased biological activity, while Mycena hyphae had fewer upregulated than downregulated genes, indicating decreased biological activity. ABA biosynthesis in G. elata was reduced by the downregulated expression of 9-cis-epoxycarotenoid dioxygenase (NCED-2), and ABA signaling was blocked by the downregulated expression of a receptor protein (PYL12-like). This is the first report to describe the role of NCED-2 and PYL12-like in breaking G. elata seed dormancy by reducing the synthesis and blocking the signaling of the germination inhibitor ABA. This study provides a theoretical basis for screening germination fungi to identify effective symbionts and for reducing ABA inhibition of G. elata seed germination.
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Affiliation(s)
- Li-Ying Ren
- College of Plant Protection, Jilin Agricultural University, Changchun 130118, China;
- Engineering Research Center of Edible and Medicinal Fungi, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
| | - Heng Zhao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Ling Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tong-Kai Zong
- Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Ministry of Education, Southwest Forestry University, Kunming 650224, China;
| | - Min Qiao
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming 650091, China
| | - Shu-Yan Liu
- College of Plant Protection, Jilin Agricultural University, Changchun 130118, China;
- Engineering Research Center of Edible and Medicinal Fungi, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
| | - Xiao-Yong Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; (H.Z.); (X.-L.L.)
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Acemi A. Polymerization degree of chitosan affects structural and compositional changes in the cell walls, membrane lipids, and proteins in the leaves of Ipomoea purpurea: An FT-IR spectroscopy study. Int J Biol Macromol 2020; 162:715-722. [PMID: 32569684 DOI: 10.1016/j.ijbiomac.2020.06.171] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/10/2020] [Accepted: 06/17/2020] [Indexed: 11/15/2022]
Abstract
This research aimed to investigate the polymerization degree (DP) -dependent effects of chitosan treatments on structural and compositional changes in certain cell wall polysaccharides (mainly lignin), membrane lipids, and proteins of in vitro-propagated Ipomoea purpurea leaves through FT-IR spectroscopy. The chitosan oligomer mixture (DP 2-15; CHI-OM) and chitosan polymer (DP 70; CHI-P) applied at 5, 10, and 20 mg L-1 concentrations induced different patterns of biomolecular changes in I. purpurea leaves. The chitosan variants enhanced the destabilization of cell membrane structures. CHI-P treatments increased the lipid structure and protein content of the membranes more than CHI-OM treatments. CHI-OM treatment was found to have the ability to induce the formation of β-sheet structures with a low number of strands, whereas CHI-P treatment was found to have the ability to trigger the formation of more extended α-helix structures in the secondary structure of proteins. CHI-P treatments increased lignin synthesis more than CHI-OM treatments. However, CHI-OM at 10 mg L-1 concentration was more effective than CHI-P treatments in the induction of cell wall polysaccharide synthesis. These findings suggest that the polymerization degree of chitosan plays a role in changing structures and compositions of the biomolecules present in the leaves of I. purpurea.
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Affiliation(s)
- Arda Acemi
- Department of Biology, Faculty of Arts and Sciences, Kocaeli University, 41001, İzmit, Kocaeli, Turkey.
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10
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Ghimire B, Son S, Kim JH, Jeong MJ. Gametophyte and embryonic ontogeny: understanding the reproductive calendar of Cypripedium japonicum Thunb. (Cypripedoideae, Orchidaceae), a lady's slipper orchid endemic to East Asia. BMC PLANT BIOLOGY 2020; 20:426. [PMID: 32933474 PMCID: PMC7493375 DOI: 10.1186/s12870-020-02589-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The genus Cypripedium L. is one of the five genera of the subfamily Cypripedioideae, members of which are commonly known as lady's slipper orchids. Cypripedium japonicum is a perennial herb native to East Asia, specifically China, Japan, and Korea. Due to its limited distribution, the species is included in the Endangered category of the IUCN Red List. RESULTS We investigated gametophyte development, including complete embryogenesis, in C. japonicum. The complete reproductive cycle is presented based on our observations. Anther development begins under the soil, and meiosis of pollen mother cells begins 3 weeks before anthesis, possibly during early April. The megaspore mother cells develop just after pollination in early May and mature in mid-late June. The pattern of embryo sac formation is bisporic, and there are six nuclei: three forming the egg apparatus, two polar nuclei, and an antipodal cell in the mature embryo sac. Triple fertilization results in the endosperm nucleus, which degenerates when the proembryo reaches the eight-to-sixteen-cell stage. CONCLUSION Our overall comparisons of the features of gametophyte and embryo development in C. japonicum suggest that previous reports on the embryology of Cypripedium are not sufficient for characterization of the entire genus. Based on the available information, a reproductive calendar showing the key reproductive events leading to embryo formation has been prepared.
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Affiliation(s)
- Balkrishna Ghimire
- Division of Forest Biodiversity, Korea National Arboretum, Pocheon, 11186, South Korea
| | - Sungwon Son
- Division of Plant Resources, Korea National Arboretum, Yongmun, 12519, South Korea
| | - Jae Hyeun Kim
- Division of Plant Resources, Korea National Arboretum, Yongmun, 12519, South Korea
| | - Mi Jin Jeong
- Division of Plant Resources, Korea National Arboretum, Yongmun, 12519, South Korea.
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11
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Fang L, Xu X, Li J, Zheng F, Li M, Yan J, Li Y, Zhang X, Li L, Ma G, Zhang A, Lv F, Wu K, Zeng S. Transcriptome analysis provides insights into the non-methylated lignin synthesis in Paphiopedilum armeniacum seed. BMC Genomics 2020; 21:524. [PMID: 32727352 PMCID: PMC7391499 DOI: 10.1186/s12864-020-06931-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 07/20/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUNDS Paphiopedilum is an important genus of the orchid family Orchidaceae and has high horticultural value. The wild populations are under threat of extinction because of overcollection and habitat destruction. Mature seeds of most Paphiopedilum species are difficult to germinate, which severely restricts their germplasm conservation and commercial production. The factors inhibiting germination are largely unknown. RESULTS In this study, large amounts of non-methylated lignin accumulated during seed maturation of Paphiopedilum armeniacum (P. armeniacum), which negatively correlates with the germination rate. The transcriptome profiles of P. armeniacum seed at different development stages were compared to explore the molecular clues for non-methylated lignin synthesis. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that a large number of genes associated with phenylpropanoid biosynthesis and phenylalanine metabolism during seed maturation were differentially expressed. Several key genes in the lignin biosynthetic pathway displayed different expression patterns during the lignification process. PAL, 4CL, HCT, and CSE upregulation was associated with C and H lignin accumulation. The expression of CCoAOMT, F5H, and COMT were maintained at a low level or down-regulated to inhibit the conversion to the typical G and S lignin. Quantitative real-time RT-PCR analysis confirmed the altered expression levels of these genes in seeds and vegetative tissues. CONCLUSIONS This work demonstrated the plasticity of natural lignin polymer assembly in seed and provided a better understanding of the molecular mechanism of seed-specific lignification process.
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Affiliation(s)
- Lin Fang
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Xin Xu
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ji Li
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Feng Zheng
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Mingzhi Li
- Independent Researcher, Guangzhou, 510555, China
| | - Jingwei Yan
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China
| | - Yuan Li
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Xinhua Zhang
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Lin Li
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Guohua Ma
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Aying Zhang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China
| | - Fubing Lv
- Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Kunlin Wu
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
| | - Songjun Zeng
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China. .,Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
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Optimization of in vitro asymbiotic seed germination protocol for Serapias vomeracea. THE EUROBIOTECH JOURNAL 2019. [DOI: 10.2478/ebtj-2019-0017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Serapias vomeracea is an economically important orchid species which is over-collected from nature, because of its glucomannan-rich tubers. Thus, optimization of in vitro culture methodology in this species is required to meet industrial needs and to secure its populations in nature. This study aimed to optimize the surface sterilization protocol for S. vomeracea seeds and to select the optimal seed germination medium by comparing the commonly used media in in vitro orchid culture. During seed surface sterilization, ethyl alcohol (EtOH) pre-treatment prior to sodium hypochlorite (NaOCl) treatment increased the disinfection success and viable seed yield when examined using the triphenyl tetrazolium chloride (TTC) seed viability test. Also, low-g force centrifugation as an additional step in the surface sterilization method separated the seeds without embryo from the viable seeds and thereby decreased potential counting errors after incubation. Comparison of media showed that solid Knudson C (KN) medium induced the highest number of germinated seeds. However, seed germination success of Lindemann (LN) and Vacin & Went (VW) media was found to be higher when the media was used in liquid form. Half-strength liquid VW was the only medium that induced higher germination success than the other full-strength media. The highest number of ungerminated seeds was found when using KN medium whereas liquid VW medium gave the lowest number. In general, protocorm formation was triggered when the media were used in liquid form. However, rhizoid elongation was suppressed in liquid media. These findings suggest that this optimized seed surface sterilization method offers a simple and effective alternative to classical methods. Additionally, solid KN medium may be considered as a cost-effective and reliable alternative to other commonly-used complex media in S. vomeracea cultures.
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Pierce S, Spada A, Caporali E, Ceriani RM, Buffa G. Enzymatic scarification of Anacamptis morio (Orchidaceae) seed facilitates lignin degradation, water uptake and germination. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:409-414. [PMID: 29350478 DOI: 10.1111/plb.12694] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 01/12/2018] [Indexed: 06/07/2023]
Abstract
The seed coat of many species contains hydrophobic lignins, and in soil the action of microbial ligninases may contribute to release from dormancy. Laboratory use of ligninases to stimulate germination is promising because of the specific action on the seed coat, whereas chemical scarification agents may also corrode the embryo. We hypothesised that exposure of Anacamptis morio (Orchidaceae) seeds to fungal laccase would stimulate germination, and that the mechanism involves lignin degradation and increased imbibition. Germination capacity in vitro was quantified with 1 U filter-sterilised laccase added to agar medium following autoclaving, compared to a 10% bleach solution (standard bleach surface sterilisation/scarification method used in orchid seed sowing). Lignin degradation was quantified using an optical method (phloroglucinol-HCl staining) combined with image analysis, following experimental pre-treatments involving immersion in laccase solution, distilled water (negative control) or bleach (positive control). Water uptake after experimental treatments was quantified as the proportion of seeds exhibiting visible uptake of an aqueous fluorochrome under UV excitation. Laccase stimulated a doubling of germination in vitro with respect to bleach surface sterilisation/scarification alone, from 23.7 to 49.8% (P = 0.007). Laccase and bleach methods both significantly decreased the optical signal of phloroglucinol (for laccase, to 79.9 ± 1.3% of controls; anova: F = 10.333, P = 0.002). Laccase resulted in a modest but highly significant (P < 0.0001) increase in water uptake with respect to the control (11.7%; cf 99.4% for bleach). Laccase scarification can stimulate germination of A. morio through a mechanism of targeted seed coat degradation. The results demonstrate the potential of this relatively non-invasive enzymatic scarification technique.
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Affiliation(s)
- S Pierce
- Department of Agricultural and Environmental Sciences (DiSAA), University of Milan, Milan, Italy
| | - A Spada
- Department of Agricultural and Environmental Sciences (DiSAA), University of Milan, Milan, Italy
| | - E Caporali
- Department of Biosciences, University of Milan, Milano, Italy
| | - R M Ceriani
- The Native Flora Centre (Centro Flora Autoctona; CFA), c/o Parco Monte Barro, Galbiate, Italy
| | - G Buffa
- Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari of Venice, Venice, Italy
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Figura T, Tylová E, Šoch J, Selosse MA, Ponert J. In vitro axenic germination and cultivation of mixotrophic Pyroloideae (Ericaceae) and their post-germination ontogenetic development. ANNALS OF BOTANY 2019; 123:625-639. [PMID: 30403767 PMCID: PMC6417480 DOI: 10.1093/aob/mcy195] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/25/2018] [Accepted: 10/06/2018] [Indexed: 05/21/2023]
Abstract
BACKGROUND AND AIMS Pyroloids, forest sub-shrubs of the Ericaceae family, are an important model for their mixotrophic nutrition, which mixes carbon from photosynthesis and from their mycorrhizal fungi. They have medical uses but are difficult to cultivate ex situ; in particular, their dust seeds contain undifferentiated, few-celled embryos, whose germination is normally fully supported by fungal partners. Their germination and early ontogenesis thus remain elusive. METHODS An optimized in vitro cultivation system of five representatives from the subfamily Pyroloideae was developed to study the strength of seed dormancy and the effect of different media and conditions (including light, gibberellins and soluble saccharides) on germination. The obtained plants were analysed for morphological, anatomical and histochemical development. KEY RESULTS Thanks to this novel cultivation method, which breaks dormancy and achieved up to 100 % germination, leafy shoots were obtained in vitro for representatives of all pyroloid genera (Moneses, Orthilia, Pyrola and Chimaphila). In all cases, the first post-germination stage is an undifferentiated structure, from which a root meristem later emerges, well before formation of an adventive shoot. CONCLUSIONS This cultivation method can be used for further research or for ex situ conservation of pyroloid species. After strong seed dormancy is broken, the tiny globular embryo of pyroloids germinates into an intermediary zone, which is functionally convergent with the protocorm of other plants with dust seeds such as orchids. Like the orchid protocorm, this intermediary zone produces a single meristem: however, unlike orchids, which produce a shoot meristem, pyroloids first generate a root meristem.
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Affiliation(s)
- Tomáš Figura
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná, Prague, Czech Republic
- Institut de Systématique, Évolution, Biodiversité (ISYEB), Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, EPHE, Paris, France
| | - Edita Tylová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná, Prague, Czech Republic
| | - Jan Šoch
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná, Prague, Czech Republic
| | - Marc-André Selosse
- Institut de Systématique, Évolution, Biodiversité (ISYEB), Muséum national d’Histoire naturelle, CNRS, Sorbonne Université, EPHE, Paris, France
- Department of Plant Taxonomy and Nature Conservation, University of Gdańsk, Wita Stwosza, Gdańsk, Poland
| | - Jan Ponert
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná, Prague, Czech Republic
- Prague Botanical Garden, Trojská, Prague, Czech Republic
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Lee YI, Chen MC, Lin L, Chung MC, Leu WM. Increased Expression of 9- Cis-Epoxycarotenoid Dioxygenase, PtNCED1, Associated With Inhibited Seed Germination in a Terrestrial Orchid, Phaius tankervilliae. FRONTIERS IN PLANT SCIENCE 2018; 9:1043. [PMID: 30065747 PMCID: PMC6056907 DOI: 10.3389/fpls.2018.01043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/27/2018] [Indexed: 05/14/2023]
Abstract
The phytohormone abscisic acid (ABA) is involved in regulating seed dormancy and germination. A crucial step of ABA biosynthesis in higher plants is the oxidative cleavage of cis-epoxycarotenoids by 9-cis-epoxycarotenoid dioxygenase (NCED). Seed development in orchids is unusual because the embryos are minute in size, without obvious histodifferentiation, and lack endosperm. To understand the regulation of ABA biosynthesis in orchid seeds, we isolated and characterized a full-length cDNA encoding an NCED homolog, PtNCED1, from developing seeds of an ornamental orchid, Phaius tankervilliae. Germination percentage was high at 90 days after pollination (DAP), when a globular embryo proper with a degenerating suspensor was evident. After 90 DAP, seed maturation was accompanied by a decrease in water content and a concomitant increase in ABA content and PtNCED1 mRNA level along with a marked decrease in germination percentage. Mature seeds pretreated with NaOCl solution lowered ABA content and improved seed germination. Moreover, after seed germination, developing protocorms could respond to dehydration stress. Dehydration of protocorms stimulated an increase in PtNCED1 level along with ABA content. Our results provide evidence of the involvement of PtNCED1 in regulating endogenous ABA content in developing seeds and protocorms. The accumulation of endogenous ABA content in orchid seeds may have a critical role in seed dormancy and the protocorm response to water stress after seed germination.
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Affiliation(s)
- Yung-I. Lee
- Department of Biology, National Museum of Natural Science, Taichung, Taiwan
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Ming-Chuan Chen
- Department of Biology, National Museum of Natural Science, Taichung, Taiwan
| | - Li Lin
- Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Mei-Chu Chung
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Wei-Ming Leu
- Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
- Advanced Plant Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
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Kendon JP, Rajaovelona L, Sandford H, Fang R, Bell J, Sarasan V. Collecting near mature and immature orchid seeds for ex situ conservation: 'in vitro collecting' as a case study. BOTANICAL STUDIES 2017; 58:34. [PMID: 28791661 PMCID: PMC5548706 DOI: 10.1186/s40529-017-0187-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 07/24/2017] [Indexed: 05/07/2023]
Abstract
BACKGROUND Lack of phenological information and efficient collecting methods are considered impediments for orchid seed collecting. This leads to opportunistic collecting as part of general seed collecting schedules that may last few weeks especially in remote areas. The study explored the feasibility of collecting near mature and immature seeds to support conservation action plans. Mature, near mature and immature seeds of orchids were collected from the wild in the Central Highlands of Madagascar (CHM). Seed capsules were collected in sterile culture medium in the wild, to prevent deterioration of seeds inside the capsule after collecting, later to be cultured under laboratory conditions. RESULTS Seed capsules collected by the in vitro collecting (IVC) method were kept in very good condition for up to 4 weeks before germination under in vitro conditions. Significantly faster and higher germination rate (p < 0.001) than mature seeds was observed in a number of taxa collected during a 3 year-long study. In some taxa even immature seeds, with no apparent sign of testa covering the embryo, germinated following IVC where mature seeds failed to germinate. CONCLUSIONS We propose that IVC method has potential to complement conventional seed collecting by increasing the germplasm that can be used in integrated conservation action plans. Improvements can be made in developing collections for taxa from biodiversity hotspots and remote areas where collecting requires considerable resources. This method can further be used on a wider selection of plants from different geographic areas and on embryo rescue programmes for economically important plants.
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Affiliation(s)
- Jonathan P. Kendon
- Natural Capital and Plant Health, Royal Botanic Gardens Kew, Richmond, Surrey TW9 3AB UK
| | - Landy Rajaovelona
- Kew Madagascar Conservation Centre, Lot II J 131 B Ambodivoanjo-Ivandry, 101 Antananarivo, Madagascar
| | - Helen Sandford
- Natural Capital and Plant Health, Royal Botanic Gardens Kew, Richmond, Surrey TW9 3AB UK
| | - Rui Fang
- Natural Capital and Plant Health, Royal Botanic Gardens Kew, Richmond, Surrey TW9 3AB UK
| | - Jake Bell
- Natural Capital and Plant Health, Royal Botanic Gardens Kew, Richmond, Surrey TW9 3AB UK
| | - Viswambharan Sarasan
- Natural Capital and Plant Health, Royal Botanic Gardens Kew, Richmond, Surrey TW9 3AB UK
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Rasmussen HN, Dixon KW, Jersáková J, Těšitelová T. Germination and seedling establishment in orchids: a complex of requirements. ANNALS OF BOTANY 2015; 116:391-402. [PMID: 26271118 PMCID: PMC4549959 DOI: 10.1093/aob/mcv087] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/08/2015] [Accepted: 04/30/2015] [Indexed: 05/03/2023]
Abstract
BACKGROUND Seedling recruitment is essential to the sustainability of any plant population. Due to the minute nature of seeds and early-stage seedlings, orchid germination in situ was for a long time practically impossible to observe, creating an obstacle towards understanding seedling site requirements and fluctuations in orchid populations. The introduction of seed packet techniques for sowing and retrieval in natural sites has brought with it important insights, but many aspects of orchid seed and germination biology remain largely unexplored. KEY CONSIDERATIONS The germination niche for orchids is extremely complex, because it is defined by requirements not only for seed lodging and germination, but also for presence of a fungal host and its substrate. A mycobiont that the seedling can parasitize is considered an essential element, and a great diversity of Basidiomycota and Ascomycota have now been identified for their role in orchid seed germination, with fungi identifiable as imperfect Rhizoctonia species predominating. Specificity patterns vary from orchid species employing a single fungal lineage to species associating individually with a limited selection of distantly related fungi. A suitable organic carbon source for the mycobiont constitutes another key requirement. Orchid germination also relies on factors that generally influence the success of plant seeds, both abiotic, such as light/shade, moisture, substrate chemistry and texture, and biotic, such as competitors and antagonists. Complexity is furthermore increased when these factors influence seeds/seedling, fungi and fungal substrate differentially. CONCLUSIONS A better understanding of germination and seedling establishment is needed for conservation of orchid populations. Due to the obligate association with a mycobiont, the germination niches in orchid species are extremely complex and varied. Microsites suitable for germination can be small and transient, and direct observation is difficult. An experimental approach using several levels of environmental manipulation/control is recommended.
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Affiliation(s)
- Hanne N Rasmussen
- Geosciences and Nature Management, University of Copenhagen, Frederiksberg C, 1958, Denmark,
| | - Kingsley W Dixon
- School of Plant Biology, The University of Western Australia and Kings Park and Botanic Garden, WA 6005, Australia and
| | - Jana Jersáková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Tamara Těšitelová
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
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Raventós J, González E, Mújica E, Bonet A. Transient Population Dynamics of Two Epiphytic Orchid Species after Hurricane Ivan: Implications for Management. Biotropica 2015. [DOI: 10.1111/btp.12231] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- José Raventós
- Departamento de Ecología; Universidad de Alicante; Carretera San Vicente del Raspeig s/n 03080 San Vicente del Raspeig Alicante Spain
| | - Elaine González
- Jardín Botánico Orquideario Soroa; Km 8 Carretera a Soroa Candelaria Artemisa Cuba
| | - Ernesto Mújica
- Jardín Botánico de Pinar del Río; ECOVIDA; Km.1,5 Hoyo del Guamá Pinar del Río Cuba
| | - Andreu Bonet
- Departamento de Ecología; Universidad de Alicante; Carretera San Vicente del Raspeig s/n 03080 San Vicente del Raspeig Alicante Spain
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