Rhizanthella gardneri - Copy (3) - Copy

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Rhizanthella gardneri:

Rhizanthella gardneri Biology 7 Manik Rustamyan

Rhizanthella gardneri:

Rhizanthella gardneri

PowerPoint Presentation:

This white leafless plant is made up of a fleshy underground stem(or tuber), which produces a flower head consisting of around 150 tightly packed, tiny flowers never emerging from the ground. It remains completely underground for its entire life. R. gardneri , also known as Western Underground Orchid, was discovered in the spring of 1928 in the Wheatbelt region of Western Australia. R. gardneri has the fewest chloroplast genes (37 only) found in any plant, and they are genes that are not involved in photosynthesis.

Rhizanthella gardneri :

Rhizanthella gardneri

PowerPoint Presentation:

This unusual orchid is critically endangered, with only fifty known plants in the wild, found in five locations in Western Australia. Because of its rarity, the locations of the orchids are a secret. They are also very difficult to find . This orchid does not photosynthesize its own food but has instead evolved a parasitic relationship with a fungus associated with the roots of the broom brush shrub. It is thought to gain its energy and nutrients as a myco -heterotroph via Ceratobasidium fungi that form ectomycorrhizas with roots of broom bush, M. scalena .

The objective of the experiment was :

The objective of the experiment was T o determine to what extent a tripartite relationship with both a specialist fungus Ceratobasidium and autotrophic host M. scalena , facilitates C ( carbon ) and N (nitrogen) transfers to R. gardneri .

The procedure:

The procedure A compartmentalized microcosm was used to investigate the R. gardneri tripartite relationship The seeds of M. scalena and R. gardneri were sterilized T he compartments were then filled with sterilized soil and the seeds of R. gardneri (innermost) and M. scalena (outermost) were added to the soil along with alginate beads of fungal inoculum The fungus used- Ceratobasidium

Microcosm design showing the whole microcosm immediately before isotope labeling:

Microcosm design showing the whole microcosm immediately before isotope labeling

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60 weeks after establishment isotopically labeled tracers were added to microcosms The first labeling experiment 13 CO 2 was applied to foliage of M. scalena plants The second labeling experiment was to assess the saprotrophic potential of the mycorrhizal fungus and its capacity to transfer soil derived organic C and N. Glycine was chosen to represent an organic C and N source All samples were analyzed for total N and C content (%). Based on the results from analysis, C and N movement from M. scalena to R. gardneri was calculated

Results of the experiment:

Results of the experiment The results from the following experiment proved that R.gardneri obtains nutrients from a fungus, which in turn derives them from an autotrophic shrub and from the soil organic substrates via saprophytic activity. Consequently, the tripartite system is not simply two plants connected by fungus, and the organisms involved in this relationship should be considered parts of two distinct systems: a fungus obtaining a steady consistent carbohydrate source and the orchid exploiting a mycorrhizal fungus for all its nutritional needs.

The main causes leading to Rhizanthella gardneri’s degradation:

The main causes leading to Rhizanthella gardneri’s degradation 1. The level of threat posed by the death of Melaleuca scalena . Rising saline water tables are causing deaths amongst Melaleuca scalena and will possibly increase in future. 2. H uman search for the orchid

Underground orchid recovery plan:

Underground orchid recovery plan monitor the plant populations undertake weed control promote the growth of Melaleuca species rehabilitate habitat promote awareness amongst all relevant land owner

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