Compare the data with the ones of your partner team

The seeds from our team on Thursday haven’t developed. The same situation appeared by the other team on Tuesday. All the seeds have remained at the same stage as in the beginning, when we put them in the petri dishes. It could be that the green pod was harvest too early and the seeds weren’t ripped. Both teams had the samples infected by bacteria or fungus. The fungus proliferates much faster than the seeds in the petri dishes. The enormous grow rate of the fungus could have a negative effect to the orchids seeds. The grow rate of the two symbionts must be in balance, otherwise a successful development isn’t possible. We have sterilized our seeds with the direct flaming method by the closed capsules. This kind of sterilization may need to be changed. We would have got a better germination of the seeds, if we had done the same treatment with NaOCI as Damian did. In his experiment, the Javel water stimulates the testa and this increases the germination capacity.

Description of the development stages from the orchid cultures



Picture 1: Development stages of orchids

 

Since the transfer of the orchid seeds to the petri dish at week 9 (28.02.2013), the seedlings haven’t changed in size and shape very much. They look almost the same as in the beginning. See picture number two.

Picture 2: the embryo in the testa (09.04.2013)

In the petri dishes with the mycorrhiza, it seems that the growth rate of the fungus and the seeds aren´t in balance. The fungus grew much faster and eliminated the seeds.
Usually the seeds start to swell after a time and the embryo then fills out the testa. See picture number tree.


Picture 3: the swollen embryo in the testa (14.03.2013)

During this time, the seeds are protected from mechanical damages by the testa. Later the testa ruptures. This process can be triggered through the increase of the seed, the mycorrhizal excretion or the ingrowth of the hyphae in the testa (www.dgfm-ev.de/sites/default/files/ZM512185Beyrle.pdf). Then a protocorm with rhizoids evolve. In the asymbiotic variant (without mycorrhiza), the rhizoids absorbs the nutrients directly from the medium. In the symbiotic variant, the seeds germination is the same as in nature. The development of the protocorm is supported by the mycorrhizal fungus, which provides the necessary nutrients.

Picture 4: Protocorm wirh rhizoids (09.04.2013)

Due to the nutrients, the protocorm will be able to grow further. After a certain period of time the roots and cotyledons will develop.

In our experiment the seeds aren’t develop in the asybiotic and the symbiotic variant. One reason could be that the capsules we used were harvested too early and therefore they aren’t  germinated.   

An assessment of the fungal specificity of the orchid sub-tribe Pterostylis

Seed Germination Experiment

Almost all orchids are depending on mycorrhizal fungi during their full life. Especially by their germination, the mycorrhizal is needed.  The seeds of the orchids are very small and only got a little stock of nutrients, therefore they require fungus to transport the necessary nutrients from the soil to the seed.

This experiment shows the relation between the orchid Pterostylis and different types of mycorrhizal fungi, which occur in east and west Australia. For this experiment they took seeds from an orchid and put them in a Petri dish with a medium, to avoid the natural variability, they took the seeds only from one orchid. Afterwards they added a specific mycorrhizal fungus to the Petri dish and could see with which fungus the orchid makes a symbiosis. Without a suitable fungus, the seed wouldn’t grow that much, because the orchid couldn’t get the nutrients out of the medium.

The result shows that the growth indices of the fungal treatments were significantly higher than the growth indices from the control. It also shows the variation in growth within the fungal treatments themselves.  Not only closely related species of mykorrhiza can have similar impacts of the germination, also less related clades can be similar. The results confirmed that the orchid Pterostylis can germinate with several mycorrhizal fungus successfully. The seed germination rate form east and west Australian fungus was not significant, so it doesn’t matter from which locality the fungus comes from. There must be other environmental influences which affect the orchid growth rate in this region.

 

 

Molecular Experiment

With the new molecular technique it is possible to produce fragments of DNA. With the agarose gel electrophoresis it is possible to see the lengths of the base pairs in a photo. In the fragments are different intron types and each of the intron type is adapted to only one clade (exception one clade, which contained with three intron types). With this information it can be easier to determine the clade of the fungus without doing a costly DNA sequencing.

In vitro - techniques

Discuss if in vitro - techniques of orchid cultivation might be a useful medium to propagate and reintroduce orchids on former habitats.

 

The development of in vitro proliferation allows us to produce a large number of the same individuals in a very short time. To produce as many individuals in the natur, it would take a much longer time. By the in vitro proliferation result all identical plants. I suspect that when wrong environmental conditions, despite the high number of species all orchids population can die, because the plants from the in vitro proliferation are genetically identical offspring from the mother plant, in this population is less genetic diversity then in a natural plant community. The result of this reduced genetic diversity, the plant can’t adapt to changing environmental conditions, as the wild variant would do. Before new plants get planted, we must know why the orchids don’t grow on this place any more. Is it because a too intensive fertilization or aren’t they able to reproduce in a natural way?
Even if so many plants are produced by in vitro and planted out, if the environment is not optimal for the orchids, the effort in the laboratory is hardly worth because the orchid can only be established in an appropriate habitat. Therefore, it is particularly important to protect the habitats of orchids.

first step

Sooo... this is my first post in my blog