Scientific approaches to Australian temperate terrestrial orchid conservation

2007 ◽  
Vol 55 (3) ◽  
pp. 293 ◽  
Author(s):  
Mark C. Brundrett

This review summarises scientific knowledge concerning the mycorrhizal associations, pollination, demographics, genetics and evolution of Australian terrestrial orchids relevant to conservation. The orchid family is highly diverse in Western Australia (WA), with over 400 recognised taxa of which 76 are Declared Rare or Priority Flora. Major threats to rare orchids in WA include habitat loss, salinity, feral animals and drought. These threats require science-based recovery actions resulting from collaborations between universities, government agencies and community groups. Fungal identification by DNA-based methods in combination with compatibility testing by germination assays has revealed a complex picture of orchid–fungus diversity and specificity. The majority of rare and common WA orchids studied have highly specific mycorrhizal associations with fungi in the Rhizoctonia alliance, but some associate with a wider diversity of fungi. These fungi may be a key factor influencing the distribution of orchids and their presence can be tested by orchid seed bait bioassays. These bioassays show that mycorrhizal fungi are concentrated in coarse organic matter that may be depleted in some habitats (e.g. by frequent fire). Mycorrhizal fungi also allow efficient propagation of terrestrial orchids for reintroduction into natural habitats and for bioassays to test habitat quality. Four categories of WA orchids are defined by the following pollination strategies: (i) nectar-producing flowers with diverse pollinators, (ii) non-rewarding flowers that mimic other plants, (iii) winter-flowering orchids that attract fungus-feeding insects and (iv) sexually deceptive orchids with relatively specific pollinators. An exceptionally high proportion of WA orchids have specific insect pollinators. Bioassays testing orchid-pollinator specificity can define habitats and separate closely related species. Other research has revealed the chemical basis for insect attraction to orchids and the ecological consequences of deceptive pollination. Genetic studies have revealed that the structure of orchid populations is influenced by pollination, seed dispersal, reproductive isolation and hybridisation. Long-term demographic studies determine the viability of orchid populations, estimate rates of transition between seedling, flowering, non-flowering and dormant states and reveal factors, such as grazing and competition, that result in declining populations. It is difficult to define potential new habitats for rare orchids because of their specific relationships with fungi and insects. An understanding of all three dimensions of orchid habitat requirements can be provided by bioassays with seed baits for fungi, flowers for insects and transplanted seedlings for orchid demography. The majority of both rare and common WA orchids have highly specific associations with pollinating insects and mycorrhizal fungi, suggesting that evolution has favoured increasing specificity in these relationships in the ancient landscapes of WA.

2020 ◽  
Vol 8 (8) ◽  
pp. 1120
Author(s):  
Hector Herrera ◽  
Tedy Sanhueza ◽  
Rodolfo Martiarena ◽  
Rafael Valadares ◽  
Alejandra Fuentes ◽  
...  

Mycorrhizal interactions of orchids are influenced by several environmental conditions. Hence, knowledge of mycorrhizal fungi associated with orchids inhabiting different ecosystems is essential to designing recovery strategies for threatened species. This study analyzes the mycorrhizal associations of terrestrial orchids colonizing grassland and understory in native ecosystems of the region of La Araucanía in southern Chile. Mycorrhizal fungi were isolated from peloton-containing roots and identified based on the sequence of the ITS region. Their capacities for seed germination were also investigated. We detected Tulasnella spp. and Ceratobasidium spp. in the pelotons of the analyzed orchids. Additionally, we showed that some Ceratobasidium isolates effectively induce seed germination to differing degrees, unlike Tulasnella spp., which, in most cases, fail to achieve protocorm growth. This process may underline a critical step in the life cycle of Tulasnella-associated orchids, whereas the Ceratobasidium-associated orchids were less specific for fungi and were effectively germinated with mycorrhizal fungi isolated from adult roots.


2009 ◽  
Vol 57 (4) ◽  
pp. 373 ◽  
Author(s):  
Magali Wright ◽  
Rob Cross ◽  
Kingsley Dixon ◽  
Tien Huynh ◽  
Ann Lawrie ◽  
...  

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.


2011 ◽  
Vol 59 (5) ◽  
pp. 480 ◽  
Author(s):  
J. Tupac Otero ◽  
Peter H. Thrall ◽  
Mark Clements ◽  
Jeremy J. Burdon ◽  
Joseph T. Miller

Fungal symbionts involved in mycorrhizal associations are known to vary considerably in both specificity and the level of benefits conferred on their plant hosts. For orchids, association with a suitable mycorrhizal fungus is vital for successful germination, growth and establishment. Using an evolutionarily distinct group of Australasian terrestrial orchids, the Pterostylidinae (Cranichiadeae: Orchidaceae), we assessed potential codiversification and the level of response between this diverse host group (~250 species) and their associated fungal symbionts. All fungal isolates recovered (~200 from 41 host species covering all major orchid clades) were identified as species of Ceratobasidium, which clustered into strongly supported groups using nuclear (ITS) and mitochondrial (ML 4–5) gene sequences. Three clades within the Pterostylidinae phylogeny showed associations with specific fungal clades. The results suggest the occurrence of local adaptation by the fungal symbionts to the orchid host, particularly in diverse and widespread host taxa. Results of cross-inoculation in vitro germination experiments revealed correlations between certain mycorrhizal fungal clades and particular orchid taxa, with germination generally being most effective when seeds were inoculated with fungal strains from the same clade as found naturally associated with the orchid species. We found only general congruence between the orchid and fungal phylogenies, suggesting that strict codivergerence between these orchids and their mycorrhizal associates has not occurred at the broad level of resolution studied.


1985 ◽  
Vol 63 (7) ◽  
pp. 1329-1333 ◽  
Author(s):  
P. G. Williams

The paper reports that previously undescribed, sterile, septate fungi (Rhizoctonia) with affinity to and attributes of orchid mycorrhizal fungi, commonly occur in pot cultures of vesicular–arbuscular (V–A) mycorrhizal fungi. Seventeen pot cultures of V–A endophytes from several sources were studied. The endophytes included unidentified organisms as well as species of Glomus, Acaulospora, and Gigaspora. A Rhizoctonia was present in every pot culture. In different cases, Rhizoctonia isolates were obtained from sporelike cells in intramatrical vesicles, extramatrical hyphae, and chlamydospores or roots of pot culture plants. In pure culture, the rhizoctonias formed pale or yellow–brown, submerged colonies composed of narrow, irregularly septate hyphae. Monilioid hyphae and terminal or intercalary, spherical chlamydospores about 12 μm in diameter developed in older mycelia. Fruiting experiments by J. H. Warcup indicated that the teleomorph of three Rhizoctonia isolates is related to Sebacina vermifera Oberwinkler, a mycorrhizal endophyte of certain Australian terrestrial orchids. Positive tests for symbiotic germination of orchid seed with one isolate are described. Pasture legumes and ryegrass plants were inoculated with mycelia of Rhizoctonia strains in the presence or absence of V–A mycorrhizal fungi. Inoculation affected plant growth only when V–A mycorrhizal fungi were present: in steamed soil containing residual inoculum of a V–A endophyte, the growth response following infection by the V–A endophyte occurred in inoculated plants several weeks earlier than in uninoculated plants; in different natural soils, inoculation increased, decreased, or had no effect on growth, depending on the strain of Rhizoctonia used.


2008 ◽  
Vol 56 (7) ◽  
pp. 609 ◽  
Author(s):  
Karen D. Sommerville ◽  
John P. Siemon ◽  
Chris B. Wood ◽  
Catherine A. Offord

Ex situ conservation of threatened terrestrial orchids requires the simultaneous conservation of their mycorrhizal associations. A method for encapsulating both seed and fungi in alginate beads (known as encapsulation–dehydration) was applied to the storage and propagation of two endangered orchid species in NSW, Australia—Pterostylis saxicola D.L.Jones & M.A.Clem. and Diuris arenaria D.L.Jones. We tested the effect of storage duration and temperature on fungal recovery and germination potential in vitro, and recorded survival for seedlings subsequently transferred to potting mix. Storage at 23°C significantly reduced fungal recovery and germination for both species after only 3 months (P < 0.05), whereas storage at 4°C significantly reduced fungal recovery for P. saxicola after 6 months (P < 0.05). Storage for 6 months at −18 and −196°C had no significant effect on the fungal recovery and germination percentages of either species. All beads transferred directly from in vitro culture to potting mix resulted in the establishment of at least one seedling, and production of a healthy tuberoid, when transferred near the commencement of the natural growing season. The encapsulation–dehydration method may have a practical application for use in ex situ conservation of other terrestrial orchids, as well as their mycorrhizal fungi.


2021 ◽  
Vol 11 (12) ◽  
pp. 5739
Author(s):  
Zhansheng Liu ◽  
Wenyan Bai

The post-earthquake retrofitting and repair process of a building is a key factor in improving its seismic capability. A thorough understanding of retrofitting methods and processes will aid in repairing post-earthquake buildings and improving seismic resilience. This study aims to develop a visualization framework for the post-earthquake retrofitting of buildings which builds models based on building information modeling (BIM) and realizes visualization using augmented reality (AR). First, multi-level representation methods and coding criteria are used to process the models for a damaged member. Then, an information collection template is designed for integrating multi-dimensional information, such as damage information, retrofitting methods, technical solutions, and construction measures. Subsequently, a BIM model is presented in three dimensions (3D) using AR. Finally, the visualization process is tested through experiments, which demonstrate the feasibility of using the framework to visualize the post-earthquake retrofitting of a building.


2017 ◽  
Vol 27 (10) ◽  
pp. R376-R377 ◽  
Author(s):  
Hui Yu ◽  
Xin Wang ◽  
Lei Cao ◽  
Lu Zhang ◽  
Qiang Jia ◽  
...  

1981 ◽  
Vol 59 (6) ◽  
pp. 1056-1060 ◽  
Author(s):  
Sharon L. Rose

Endemic plants of the Sonoran Desert of Baja California were sampled for mycorrhizal associations. Eight of the 10 plant species examined were colonized by vesicular–arbuscular (VA) mycorrhizal fungi. Soil sievings revealed chlamydospores of three VA mycorrhizal Glomus spp.; G. microcarpus, G. fasciculatus, and G. macrocarpus. At the time of sampling, the populations of VA fungal spores in the soil were low, with one to five chlamydospores per 100 g soil sample.


Lankesteriana ◽  
2015 ◽  
Vol 7 (1-2) ◽  
Author(s):  
Emily McQualter ◽  
Rob Cross ◽  
Cassandra McLean ◽  
Pauline Ladiges

Most members of the genus Prasophyllum (Leek Orchids) are threatened and restricted in distribution in Australia. Prasophyllum species are obligate mycotrophic plants and current conservation proto- cols for terrestrial orchids in Australia require propa- gation with symbiotic mycorrhizal fungi. Unfortunately there is a paucity of knowledge regard- ing the mycosymbiont in this genus, hampering con- servation and re-introduction efforts.


2006 ◽  
Vol 12 (2) ◽  
pp. 155-169
Author(s):  
Darko Lacmanović

Sales management acitivities such as monitoring, directing, evaluation and rewarding represents useful ways for increasing the salesperson job satisfaction and organizational commitment. Motivating the sales effort ussually include three dimensions: intensivity, persistence and choice. By inspiring salespeople on greater job commitment, sales managers keep managerial tools to stimulate latent sales efforts and performance. Rewarding system based on »straight« salary result in unmotivated sales personnel who, in that case, connect their work engagement solely with realization of working hours not with realization of sales volume. Segmentation of sales force, grouping the salespersons according to their motivation needs and offering them diverse rewarding systems per each group, presents inovative approach to challenges of motivation the salespeople.


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