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Jarvis-Lowry B, Harrington KC, Ghanizadeh H, Robertson AW. Viability and dormancy of the Clematis vitalba aerial seed bank. Plant Biol (Stuttg) 2024; 26:457-466. [PMID: 38407522 DOI: 10.1111/plb.13629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 01/17/2024] [Indexed: 02/27/2024]
Abstract
Old man's beard (Clematis vitalba L.) is a liana species that has become invasive in many areas of its introduced range. Seeds are produced in abundance and are both physiologically and morphologically dormant upon maturity. To understand the importance of seeds to its invasiveness, changes in viability and dormancy of the aerial seed bank were tracked throughout the after-ripening period and during storage. Seeds collected every second month for 2 years were subjected to germination tests. Other seeds stored in outdoor ambient conditions or in a dry, chilled state were dissected before, during, and after imbibition, as well as during incubation, to measure embryo size. Less than 72% of seeds on the mother plant were viable. Viable seeds remained completely morpho-physiologically dormant throughout autumn, even when treated with nitrate. Physiological dormancy declined in response to seasonal changes, yet morphological dormancy did not change until seeds had been exposed to appropriate germination conditions for several days. Fully dormant autumn seeds decayed at higher rates during incubation than partially or fully after-ripened seeds, which were also more germinable and less dormant. Furthermore, seeds incubated in complete darkness were more likely to decay or remain dormant than those exposed to light. This study demonstrates that fewer than three-quarters of seeds produced are viable and further decay occurs after dispersal, yet total fertility is still very high, with enormous propagule pressure from seeds alone. Viable seeds are protected with two forms of dormancy; morphological dormancy requires additional germination cues in order to break after seasonal changes break physiological dormancy.
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Affiliation(s)
- B Jarvis-Lowry
- School of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - K C Harrington
- School of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - H Ghanizadeh
- School of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - A W Robertson
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
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Walker M, Pérez M, Steinbrecher T, Gawthrop F, Pavlović I, Novák O, Tarkowská D, Strnad M, Marone F, Nakabayashi K, Leubner-Metzger G. Molecular mechanisms and hormonal regulation underpinning morphological dormancy: a case study using Apium graveolens (Apiaceae). Plant J 2021; 108:1020-1036. [PMID: 34510583 DOI: 10.1111/tpj.15489] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
Underdeveloped (small) embryos embedded in abundant endosperm tissue, and thus having morphological dormancy (MD) or morphophysiological dormancy (MPD), are considered to be the ancestral state in seed dormancy evolution. This trait is retained in the Apiaceae family, which provides excellent model systems for investigating the underpinning mechanisms. We investigated Apium graveolens (celery) MD by combined innovative imaging and embryo growth assays with the quantification of hormone metabolism, as well as the analysis of hormone and cell-wall related gene expression. The integrated experimental results demonstrated that embryo growth occurred inside imbibed celery fruits in association with endosperm degradation, and that a critical embryo size was required for radicle emergence. The regulation of these processes depends on gene expression leading to gibberellin and indole-3-acetic acid (IAA) production by the embryo and on crosstalk between the fruit compartments. ABA degradation associated with distinct spatiotemporal patterns in ABA sensitivity control embryo growth, endosperm breakdown and radicle emergence. This complex interaction between gibberellins, IAA and ABA metabolism, and changes in the tissue-specific sensitivities to these hormones is distinct from non-MD seeds. We conclude that the embryo growth to reach the critical size and the associated endosperm breakdown inside MD fruits constitute a unique germination programme.
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Affiliation(s)
- Matthew Walker
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
- Tozer Seeds, Tozer Seeds Ltd, Cobham, KT11 3EH, UK
| | - Marta Pérez
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Tina Steinbrecher
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | | | - Iva Pavlović
- Laboratory of Growth Regulators, Institute of Experimental Botany, Czech Academy of Sciences and Faculty of Science, Palacký University Olomouc, Olomouc, CZ-78371, Czech Republic
| | - Ondřej Novák
- Laboratory of Growth Regulators, Institute of Experimental Botany, Czech Academy of Sciences and Faculty of Science, Palacký University Olomouc, Olomouc, CZ-78371, Czech Republic
| | - Danuše Tarkowská
- Laboratory of Growth Regulators, Institute of Experimental Botany, Czech Academy of Sciences and Faculty of Science, Palacký University Olomouc, Olomouc, CZ-78371, Czech Republic
| | - Miroslav Strnad
- Laboratory of Growth Regulators, Institute of Experimental Botany, Czech Academy of Sciences and Faculty of Science, Palacký University Olomouc, Olomouc, CZ-78371, Czech Republic
| | - Federica Marone
- Swiss Light Source, Paul Scherrer Institute, Villigen, CH-5232, Switzerland
| | - Kazumi Nakabayashi
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Gerhard Leubner-Metzger
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
- Laboratory of Growth Regulators, Institute of Experimental Botany, Czech Academy of Sciences and Faculty of Science, Palacký University Olomouc, Olomouc, CZ-78371, Czech Republic
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Athugala YS, Gehan Jayasuriya KMG, Gunaratne AMTA, Baskin CC. Seed dormancy of 80 tropical montane forest species in Sri Lanka, the first dormancy profile for a tropical montane forest community. Plant Biol (Stuttg) 2021; 23:293-299. [PMID: 33091220 DOI: 10.1111/plb.13203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
Community-level seed dormancy studies are important in understanding the dynamics of plant communities and adaptations of species to their habitat. Our aim was to develop a seed dormancy profile for tropical montane forests of Sri Lanka, which are a global biodiversity hotspot, and compare it to the profile made using a world database for this vegetation type. Germination, imbibition and embryo length : seed length ratio of seeds were determined for 80 Sri Lankan montane forest species. Seeds of 31 species were fast-germinating with a median length of germination (MLG) <30 days and the remaining 49 were slow-germinating with MLG >30 days. Embryos of six fast-germinating species grew prior to radicle emergence, indicating morphological dormancy (MD). The other 25 fast-germinating species had non-dormant (ND) seeds. Manually scarified seeds of two species imbibed significantly more water than non-scarified seeds, revealing physical dormancy (PY). Embryos of 20 slow-germinating species grew prior to radicle emergence, confirming morpho-physiological dormancy (MPD). The remaining slow-germinating species had a fully developed embryo and thus physiological dormancy (PD). The percentage of species with ND seeds and with MD, MDP, PD and PY was 31, 7.5, 25, 34 and 2.5, respectively. Species with dormant seeds (70%) dominate the Sri Lankan montane forest community similar to the world database, with 85% dormant seeds. Seed dormancy may be an adaptation that prevents seeds from germinating during the Sri Lankan dry season from December to March when conditions are unfavourable for seedling growth due to low water availability.
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Affiliation(s)
- Y S Athugala
- Department of Botany, University of Peradeniya, Peradeniya, Sri Lanka
- Postgraduate Institute of Science, University of Peradeniya, Peradeniya, Sri Lanka
| | - K M G Gehan Jayasuriya
- Department of Botany, University of Peradeniya, Peradeniya, Sri Lanka
- Postgraduate Institute of Science, University of Peradeniya, Peradeniya, Sri Lanka
| | - A M T A Gunaratne
- Department of Botany, University of Peradeniya, Peradeniya, Sri Lanka
- Postgraduate Institute of Science, University of Peradeniya, Peradeniya, Sri Lanka
| | - C C Baskin
- Department of Biology, University of Kentucky, Lexington, KY, USA
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
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Blandino C, Fernández‐Pascual E, Marin M, Vernet A, Pritchard HW. Seed ecology of the geophyte Conopodium majus (Apiaceae), indicator species of ancient woodland understories and oligotrophic meadows. Plant Biol (Stuttg) 2019; 21:487-497. [PMID: 29972724 PMCID: PMC6492144 DOI: 10.1111/plb.12872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 06/30/2018] [Indexed: 06/01/2023]
Abstract
Conopodium majus is a geophyte with pseudomonocotyly, distributed in Atlantic Europe. It is an indicator of two declining European habitats: ancient woodland understories and oligotrophic hay meadows. Attempts to reintroduce it by seed have been hindered by scarce seedling emergence and limited knowledge of its seed biology. Micro-CT scanning was used to assess pseudomonocotyly. Embryo growth and germination were studied in the laboratory and the field, using dissection and image analysis. The effects of temperature, light, nitrate and GA3 on germination were tested. Seed desiccation tolerance was investigated by storage at different RHs and by drying seeds at different stages of embryo growth. Seeds possess morphological but not physiological dormancy. Embryo growth and germination were promoted by temperatures between 0 and 5 °C, arrested above 10 °C, and indifferent to alternating temperatures, light, nitrate and GA3 . Pseudomonocotyly appears to result from cotyledon fusion. While seeds tolerated drying to 15% RH and storage for 1 year at 20 °C, viability was lost when storage was at 60% RH. Seeds imbibed at 5 °C for 84 days had significant internal embryo growth but were still able to tolerate drying to 15% RH. Reproduction by seed in C. majus follows a strategy shared by geophytes adapted to deciduous temperate forests. The evolution of fused cotyledons may enable the radicle and the hypocotyl to reach deeper into the soil where a tuber can develop. The embryo is capable of growth within the seed at low temperatures so that germination is timed for early spring.
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Affiliation(s)
- C. Blandino
- Comparative Plant and Fungal BiologyRoyal Botanic Gardens KewWest SussexUK
- Earth and Environmental Sciences DepartmentUniversity of PaviaPaviaItaly
| | - E. Fernández‐Pascual
- Comparative Plant and Fungal BiologyRoyal Botanic Gardens KewWest SussexUK
- Departamento de Biología de Organismos y SistemasUniversidad de OviedoOviedo/UviéuSpain
| | - M. Marin
- Earth and Environmental Sciences DepartmentUniversity of PaviaPaviaItaly
- Scotia SeedsBrechinUK
| | - A. Vernet
- Division of Cardiovascular MedicineWellcome Trust Centre For Human GeneticsRadcliffeUK
| | - H. W. Pritchard
- Comparative Plant and Fungal BiologyRoyal Botanic Gardens KewWest SussexUK
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Hoyle GL, Cordiner H, Good RB, Nicotra AB. Effects of reduced winter duration on seed dormancy and germination in six populations of the alpine herb Aciphyllya glacialis (Apiaceae). Conserv Physiol 2014; 2:cou015. [PMID: 27293636 PMCID: PMC4806741 DOI: 10.1093/conphys/cou015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 03/02/2014] [Accepted: 03/27/2014] [Indexed: 05/13/2023]
Abstract
The life stages of seed germination and seedling establishment play a vital role in maintaining plant populations and determining range dynamics of species. Thus, it is not surprising that specific germination requirements and dormancy mechanisms have evolved in all major angiosperm clades. In a rapidly changing climate, we face growing pressure to manage, conserve and restore native plant species and communities. To achieve these aims, we require solid knowledge of whether and how seed germination requirements and dormancy status vary between different populations of a given species and how germination strategies may be affected by warming climatic conditions. We assessed the effect of decreasing durations of cold stratification (i.e. conditions representing a shortened winter as predicted under climate change) on germination and dormancy of the alpine herb Aciphylla glacialis. Our results confirmed previous research showing that A. glacialis seeds possess physiological dormancy that can be alleviated by cold stratification. In addition, the results demonstrated that A. glacialis seeds have underdeveloped embryos at dispersal; these grow to germinable size following 4-9 weeks at both constant 5°C and 10-5°C (day-night) temperatures. We conclude that A. glacialis exhibits morphophysiological dormancy. Furthermore, we found that the final percentage germination and dormancy status varied significantly among natural populations and that this variation did not correlate with elevation at the site of seed origin. Seeds germinated following 6-8 weeks of cold stratification, and seedlings showed no detrimental effects as a result of shorter stratification periods. Together, these results suggest that reduced duration of winter is unlikely to have direct negative impacts on germination or early seedling growth in A. glacialis. The causes and implications of the population variation in germination traits are discussed.
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Affiliation(s)
- G. L. Hoyle
- Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
| | - H. Cordiner
- Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
| | - R. B. Good
- Australian National Botanical Gardens, Clunies Ross Street, Acton, Canberra, ACT 2601, Australia
- Fenner School of the Environment, Australian National University, Canberra, ACT 0200, Australia
| | - A. B. Nicotra
- Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
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