Germination and seedling establishment in orchids: a complex of requirements

Rasmussen, Henrik; Dixon, Kingsley W.; Jersáková, Jana; Těšitelová, Tamara

doi:10.1093/aob/mcv087

Cited by 234 publications

(219 citation statements)

References 106 publications

(92 reference statements)

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“…Orchids fully rely on symbiotic fungi for carbon and nutrients at least during the very early developmental stages (Bidartondo & Read, ; Stöckel et al ., ), which necessitates a strong stimulus and thus higher specificity (Dearnaley et al ., ). The notable overlap of fungal symbiont communities of seedlings and adult orchids is also consistent with higher specificity (Rasmussen et al ., ; Waud et al ., ). Most orchid species develop an autotrophic habit in the adult stages, but many species remain partly or fully mycoheterotrophic (Gebauer et al ., ).…”

Section: Discussionmentioning

confidence: 99%

Host preference and network properties in biotrophic plant–fungal associations

et al. 2017

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Analytical methods can offer insights into the structure of biological networks, but mechanisms that determine the structure of these networks remain unclear. We conducted a synthesis based on 111 previously published datasets to assess a range of ecological and evolutionary mechanisms that may influence the plant-associated fungal interaction networks. We calculated the relative host effect on fungal community composition and compared nestedness and modularity among different mycorrhizal types and endophytic fungal guilds. We also assessed how plant-fungal network structure was related to host phylogeny, environmental and sampling properties. Orchid mycorrhizal fungal communities responded most strongly to host identity, but the effect of host was similar among all other fungal guilds. Community nestedness, which did not differ among fungal guilds, declined significantly with increasing mean annual precipitation on a global scale. Orchid and ericoid mycorrhizal fungal communities were more modular than ectomycorrhizal and root endophytic communities, with arbuscular mycorrhizal fungi in an intermediate position. Network properties among a broad suite of plant-associated fungi were largely comparable and generally unrelated to phylogenetic distance among hosts. Instead, network metrics were predominantly affected by sampling and matrix properties, indicating the importance of study design in properly inferring ecological patterns.

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Section: Discussionmentioning

confidence: 99%

Host preference and network properties in biotrophic plant–fungal associations

et al. 2017

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“…100 seeds per seed packet. This specific nylon mesh was chosen to ensure the dry orchid seeds are retained and because it is penetrable for water and fungal hyphae and durable for several years in the soil (Rasmussen et al., ). The packets were sealed with an impulse sealer (ME‐300HC; MoFix GmbH, Bad Rappenau, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…Bernard () and Burgeff () were the first to describe pelotons (intracellular coils of fungal hyphae) as the distinctive structures of orchid mycorrhizas and to realise that fungi are essential for successful orchid seed germination (Bernard, ; Burgeff, ; Smith & Read, ), however, the complex of requirements determining germination and establishment is still under study (Rasmussen, Dixon, Jersáková, & Těšitelová, ). Orchid seeds are very small ranging in length from c .…”

Section: Introductionmentioning

confidence: 99%

Stable isotope signatures of underground seedlings reveal the organic matter gained by adult orchids from mycorrhizal fungi

2018

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Orchids produce dust seeds dependent on the provision of organic carbon by mycorrhizal fungi for their early development stages. Hence, all chlorophyllous orchids experience a dramatic switch in trophic strategies from initial mycoheterotrophy to either autotrophy or partial mycoheterotrophy during ontogeny. Yet, the degree to which partially mycoheterotrophic orchids gain carbon from their mycorrhizal fungi is unclear based on existing approaches. Here, we propose a novel approach to quantify the fungal‐derived organic matter gain of chlorophyllous mature orchids mycorrhizal with rhizoctonia fungi, using the stable isotope signatures of their fully mycoheterotrophic (FMH) seedlings in a linear two‐source mixing model. We conducted a field germination experiment with seven orchid species and measured carbon, nitrogen and hydrogen stable isotope natural abundances and nitrogen concentrations of mature orchids, underground seedlings, and autotrophic references. After in situ burial for 19–30 months, germination rates varied considerably among five orchid species and failed for two. On average, underground seedlings were enriched in 13C and 15N relative to mature orchids and had higher nitrogen concentrations. Using the mean enrichment factors ε13C and ε2H of seedlings as FMH endpoint, the organic matter gain derived by mature orchids from mycorrhizas was c. 20%. Chlorophyllous orchids mycorrhizal with rhizoctonias are predisposed to partially mycoheterotrophic nutrition due to their initially mycoheterotrophic seedling stage. We show that the carbon and hydrogen isotope abundances of underground seedlings can be used in an improved mixing‐model to identify a significant proportion of fungal‐derived organic matter in mature orchids. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13042/suppinfo is available for this article.

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“…Because orchid seeds are minute, the first life stages of seedlings previously defied observation, but now experimental sowing in the field constitutes a useful routine procedure for identifying germination requirements (Rasmussen et al, 2015). The germination of terrestrial orchids is the most sensitive period of their life, because of their seed structure and their mycorrhizal fungus relationships.…”

Section: Introductionmentioning

confidence: 99%

Germination Traits of Adriatic Lizard Orchid (Himantoglossum Adriaticum) in Hungary

Gilián¹,

Bódis²,

Eszeki³

et al. 2018

Appl. Ecol. Env. Res.

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Abstract:The germination of the orchids is the most sensitive period of their life. In case of the extremely rare Himantoglossum adriaticum in Hungary, no such information has been published yet. Our aim is to present the results of the in situ and the ex situ germination of H. adriaticum seeds originate in West Hungary. There were 10-10 seed packets sowed 10-20 cm far-, and 3-3 as control 10 m away from the living mother plants on the natural habitats of Keszthelyi-hills and of Sümeg-Tapolca region. The success of germination was significantly higher close to the mother plant than in the control packets either 8 or 11 months after sowing on both places and was a bit better in Keszthely than on Sümeg-Tapolca region. Parallelly with it we sowed the seeds of same origin into six flasks, onto Fast medium in the orchid laboratory of Eötvös Loránd University's Botanical Garden in Budapest. During this ex situ germination, the first protocorm was appeared 9 months after sowing. The germination was outstanding only in one flask. Our results show, that the germination in the natural habitat was much higher than in vitro on the generally used artificial media.

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Germination and seedling establishment in orchids: a complex of requirements

Cited by 234 publications

References 106 publications

Host preference and network properties in biotrophic plant–fungal associations

Host preference and network properties in biotrophic plant–fungal associations

Stable isotope signatures of underground seedlings reveal the organic matter gained by adult orchids from mycorrhizal fungi

Germination Traits of Adriatic Lizard Orchid (Himantoglossum Adriaticum) in Hungary

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