scholarly journals Tulasnella calospora (UAMH 9824) retains its effectiveness at facilitating orchid symbiotic germination in vitro after two decades of subculturing

2021 ◽  
Vol 62 (1) ◽  
Author(s):  
Lawrence W. Zettler ◽  
Caleb J. Dvorak
Keyword(s):  
Mycorrhizal Fungi ◽  
Terrestrial Orchid ◽  
Orchid Species ◽  
The North ◽  
Symbiotic Germination ◽  
Germinating Seeds ◽  
Tulasnella Calospora

Abstract Background The technique of symbiotic germination—using mycorrhizal fungi to propagate orchids from seed in vitro—has been used as one method to cultivate orchids in North America and abroad for > 30 years. A long-held assumption is that mycorrhizal fungi used for this purpose lose their effectiveness at germinating seeds over time with repeated subculturing. Results We provide evidence for the lingering efficacy of one particular strain of Tulasnella calospora (266; UAMH 9824) to stimulate seed germination exemplified by the North American terrestrial orchid, Spiranthes cernua, as a case study. This fungus was originally acquired from roots from Spiranthes brevilabris in 1999 and sub-cultured during the two decades since. Seeds inoculated with the fungus in vitro developed to an advanced protocorm stage after 16 days, and leaf elongation was pronounced after 42 days. In a pilot study, seedlings co-cultured with Tulasnella calospora 266 were deflasked after 331 days and later transferred to soil under greenhouse conditions where they eventually initiated anthesis. During the course of two decades, seeds of 39 orchid species, cultivars and hybrids spanning 21 genera, germinated in vitro co-cultured with Tulasnella calospora 266. These orchids included temperate terrestrials and tropical epiphytes alike. Conclusions The sustained effectiveness of this fungus is noteworthy because it argues against the concept of mycorrhizal fungi losing their symbiotic capability through prolonged subculturing. This study serves as an example of why in situ habitat preservation is essential for the conservation of orchids as a source of potentially useful mycorrhizal fungi.

Specificity of the Associations Between Microtis parviflora (Orchidaceae) and Its Mycorrhizal Fungi

1995 ◽  
Vol 43 (1) ◽  
pp. 85 ◽  
Author(s):  
AJ Perkins ◽  
G Masuhara ◽  
PA Mcgee
Keyword(s):  
Rhizoctonia Solani ◽  
Mycorrhizal Fungi ◽  
Rate Of Development ◽  
Germinating Seeds

The specificity between Microtis parviflora R.Br. and its mycorrhizal associates was examined in situ and in vitro. Two fungi, Epulorhiza repens (Bernard) Moore and Epulorhiza sp. Moore (synonym Rhizoctonia globularis), were isolated from the roots and protocorms of the orchid from the field. In the laboratory, these fungi and three others that form mycorrhizae with other orchids and two others that are saprophytes, initiated mycorrhizae with M. parviflora. Two pathogenic isolates of Rhizoctonia solani Kuehn killed the germinating seeds. The addition of sucrose to the germination media increased growth and rate of development of seedlings.

scholarly journals Propagation and reintroduction of Caladenia

2009 ◽  
Vol 57 (4) ◽  
pp. 373 ◽  
Author(s):  
Magali Wright ◽  
Rob Cross ◽  
Kingsley Dixon ◽  
Tien Huynh ◽  
Ann Lawrie ◽  
...  
Keyword(s):  
Conservation Planning ◽  
Mycorrhizal Fungi ◽  
Ex Situ ◽  
Terrestrial Orchid ◽  
Natural Habitats ◽  
Nurse Plants ◽  
Mycorrhizal Associations ◽  
Symbiotic Germination ◽  
Growing Conditions

Many Caladenia species have been reduced to extremely small and/or fragmented populations, and reintroduction/translocation into natural or rehabilitated habitats, by using ex situ propagated plants or via direct seeding, represents an important adjunct in conservation planning. However, Caladenia species are some of the most difficult terrestrial orchid taxa to propagate, in part because of the specificity of the mycorrhizal associations and the need to provide growing conditions that suit both the mycorrhizal fungi and Caladenia plants. The present paper reviews recent advances in Caladenia propagation and reintroduction methods, including in vitro seed germination, transferral from in vitro to nursery environments, ex vitro symbiotic germination (germination in inoculated nursery media), nursery cultivation, the use of nurse plants and reintroduction of Caladenia into natural habitats by using seed, dormant tubers or growing plants. Techniques discussed in the present paper increase the options for future Caladenia conservation programs, especially for those species currently on the brink of extinction.

scholarly journals An expanded role for in vitro symbiotic seed germination as a conservation tool: two case studies in North America (Platanthera leucophaea and Epidendrum nocturnum)

Lankesteriana ◽  
2015 ◽  
Vol 7 (1-2) ◽  
Author(s):  
Emily Massey ◽  
Lawrence Zettler
Keyword(s):  
North America ◽  
Seed Germination ◽  
Case Studies ◽  
Mycorrhizal Fungi ◽  
Orchid Species ◽  
Symbiotic Germination ◽  
Symbiotic Seed Germination ◽  
Platanthera Leucophaea

Interest in using mycorrhizal fungi to cultivate orchids from seed in vitro (=symbiotic seed germina- tion) has intensified in recent years and this approach is now an important conservation tool worldwide. In North America, symbiotic germination has been attempted for a growing number of orchid species in peril as a means to acquire seedlings suitable for reintroduction.

scholarly journals Is the Distribution of Two Rare Orchis Sister Species Limited by Their Main Mycobiont?

Diversity ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 262
Author(s):  
Jacopo Calevo ◽  
Samuele Voyron ◽  
Enrico Ercole ◽  
Mariangela Girlanda
Keyword(s):  
Mycorrhizal Fungi ◽  
Causal Link ◽  
Sister Species ◽  
In Vitro Assays ◽  
Its2 Region ◽  
Geographical Pattern ◽  
Germinating Seeds ◽  
Globally Distributed ◽  
Native Host

As orchids rely on their mycorrhizal fungi for nutrient supply, their spatial range is dependent on the distribution of orchid mycorrhizal (OM) fungi. We addressed possible correlations between mycorrhizal specificity and the geographic distribution of orchids and OM fungi in three populations of the rare sister species Orchis patens and O. canariensis. Metabarcoding of the fungal ITS2 region indicated that, although adult plants of either species were colonized by several ceratobasidioid, tulasnelloid, sebacinoid and serendipitoid fungi, the mycobiont spectra were dominated by Tulasnella helicospora (which occurred in 100% of examined plants with high read numbers), which is a globally distributed fungus. In vitro assays with a T. helicospora isolate obtained from O. patens indicated the effectiveness of this OM fungus at germinating seeds of its native host. At a local scale, higher read numbers for T. helicospora were found in soil samples collected underneath O. patens roots than at locations unoccupied by the orchid. Although these findings suggest that the geographical pattern of the main fungal symbiont does not limit the distribution of O. patens and O. canariensis at this scale, the actual causal link between orchid and OM fungal occurrence/abundance still needs to be better understood.

scholarly journals Asymbiotic in vitro germination and seed quality assessment of Australian terrestrial orchids

2012 ◽  
Vol 60 (7) ◽  
pp. 592 ◽  
Author(s):  
Nicole Dowling ◽  
Manfred Jusaitis
Keyword(s):  
Seed Quality ◽  
Culture Media ◽  
Vital Staining ◽  
Terrestrial Orchid ◽  
Triphenyltetrazolium Chloride ◽  
Asymbiotic Seed Germination ◽  
Orchid Species ◽  
Terrestrial Orchids ◽  
Asymbiotic Germination

Determining the seed quality and germination requirements for threatened orchid species in storage is vital for future conservation efforts. Seeds of many Australian terrestrial orchid species are held in conservation collections around the country, but few have been germinated in vitro, fuelling concerns over their long-term viability. This study tested three methods of assessing orchid seed quality; asymbiotic germination was compared with vital staining using triphenyltetrazolium chloride or fluorescein diacetate. Six culture media were examined for efficacy in promoting asymbiotic seed germination of four Australian terrestrial orchid species (Pterostylis nutans, Microtis arenaria, Thelymitra pauciflora and Prasophyllum pruinosum). Germination occurred on all media but germination rates were consistently highest on BM1 and development was most advanced on BM1, P723 and Malmgren media. Subsequent trials tested the efficacy of BM1 for asymbiotic germination of additional genera (Caladenia, Calochilus and Diuris), several congeneric species, and two species collected from several different provenances within each of their ranges. The results indicate that asymbiotic germination on BM1 medium is an effective technique for testing the performance of Australian terrestrial orchid seeds. The efficacy of vital stains to determine seed viability, however, remains uncertain, as significant disagreement between degree of staining and germinability was observed for some species.

Associated fungi, symbiotic germination and in vitro seedling development of the rare Andean terrestrial orchid Chloraea riojana

Flora ◽  
2016 ◽  
Vol 224 ◽  
pp. 106-111 ◽  
Author(s):  
Sebastián Fracchia ◽  
Adriana Aranda-Rickert ◽  
Carolina Rothen ◽  
Silvana Sede
Keyword(s):  
Seedling Development ◽  
Terrestrial Orchid ◽  
Symbiotic Germination

scholarly journals Understanding the distribution of three species of epiphytic orchids in temperate Australian rainforest by investigation of their host and fungal associates

Lankesteriana ◽  
2015 ◽  
Vol 7 (1-2) ◽  
Author(s):  
Kelli Gowland ◽  
Ulrike Mathesius ◽  
Mark Clements ◽  
Adrienne Nicotra
Keyword(s):  
Mycorrhizal Fungi ◽  
Local Environment ◽  
Direct Consequence ◽  
Environmental Constraints ◽  
Terrestrial Orchid ◽  
Orchid Species ◽  
Epiphytic Orchids ◽  
Carbon Transfer ◽  
Orchid Mycorrhizal Fungi ◽  
Fungal Associates

Understanding the environmental constraints that affect species distributions are critical to the mainte- nance of biodiversity. The abundance of epiphytic organisms, those that grow on another substrate, such as a tree or rock, is a direct consequence of the avail- ability and distribution of these substrates (Ackerman et al. 1989). In the case of epiphytic orchids it is also due to the presence of orchid mycorrhizal fungi (OMF). For an orchid, crucial to its germination and establishment, is its association with an OMF. The OMF provides a carbon source to the developing orchid embryo (Rasmussen 1995). Although recipro- cal carbon transfer has been demonstrated in mature plants of a green, terrestrial, orchid species, Goodyera repens (Cameron et al. 2006), it is generally believed that OMF receive no immediate benefit from their association with orchids. Therefore, it would appear intuitive that orchids would associate with all OMF available within their local environment and that they would actively seek this association. 

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