Hello all,
I am studying the effect of sugars on rooting of Dianthus sp. in tissue culture for my internship report and I grew some plants on medium that did not contain any sucrose. The medium did contain 2.46 g/L McCown Woody Plant Medium, 0,1 mg/L IBA and 6 g/L micro agar. Strangely the plants grew just as good as the media that did contain sucrose, and after five weeks the are still growing and of good quality. Could it be that the plants are using the micro agar as a carbon source?
It is unlikely that your plants are using agar as a significant sugar source. Sucrose addition to media tends to make the most difference in the very early stages of plant growth. Once the plant is established and growing then the plant will produce its own sucrose via the dark rections of photosynthesis.
It is entirely possible that your seeds have enough sugars stored within them to get the plants established and to the point where they are producing their own sucrose. There might still be phenotypes associated with sucrose content in the media (sucrose is a prolific signalling molecule after all) but I wouldn't expect your plants to die due to the lack of it.
Having said that if your plants look different under a no sucrose regime than previous experiments in your lab under similar conditions then it is possible that your batch of agar is contaminated with sugar and you would want to find a way to test that. I have never done this but my first try would be to soak some agar in cold water (the agar won't dissolve without heating but mobilisable sugars should dissolve), centrifuge your sample to pellet the undissolved agar and take the supernatant, then do a test for sugars (perhaps use Benedicts reagent)
Agarose is a linear polymer consisting of alternating D-galactose and 3,6-anhydro-L-galactopyranose linked by α-(1→3) and β-(1→4) glycosidic bonds.
Plants don't produce the enzymes necessary to digest it.
One of the advantages of using agarose is that is inert to most organisms.
You didn't mention about your culture vessel type. If the vessel can let carbon dioxide to be exchanged easily between outside and inside of the vessel, the autotrophic ability of Dianthus plants can be enhanced, resulted in their growth as good as those on sugar-containing medium.
Hello, I studied the rooting in papaya using a mineral as a support and with gas exchange. The liquid culture medium, without sucrose, ie photoautotrophic conditions and obtained excellent results in rooting
The sucrose addition is required to conduct the experiment in vitro, as a carbohydrate source in the culture media, aiming to ensure energy support for plant growth and development. However, i agree with the teacher Quynh, the natural ventilation of the culture flasks favors the normal development of plants.
The natural ventilation of the test tubes can be controlled by partial sealing (with natural ventilation). Example: the test tubes can be closed with UNIFIL®C40 filter paper and then aluminum foil placed on top of the filter paper, with a 0.5-cm diameter central aperture to provide natural ventilation. Whereas in the fully sealed treatment (with no ventilation) the test tubes be closed with aluminum foil without a central opening.
Hello,
Normally, Agar does not contain sucrose and vitroplants can't digest the components of this gelling product... Agar is often used as a solidifier of the culture medium and also as a support for the explants and for the vitroplants.
For growing the plants under invitro condition, sucrose is added as a source of carbon source. Agar is added only as a solidifying agent. Complex carbohydrate like agar is not break down into sucrose.
In the earlier stage plant cells in the callus unable to carry out photosynthesis. That means it unable to fulfil their energy requirements. That's the main function of sugar in culture medium. Agar is a complex polysaccharide but those juvenile plant cells unable digest those kind higher molecules.
You did ask: if PLANTS in tubes with medium need sugar.as long as they are not rooted, they need sucrose. But they are SHOOTS, not plants. As soon as they are rooted, they dont need extra sucrose. As they use the ability to photosynthesis
The vitroplant don't have an enzymes necessary to digest the composition of Agar, and they need a sugar easy assimilate for a good response
Hello Pim. If you are trying to root in vitro Dianthus shoots well developped (in ventilated vessel under light) your results seem not surprising. The shoot and leaves are photosynthesising and produce sugars for the growh of roots and the new plant.
Everyting is dependent from light source/conditions. Rooting does niot require external carbohydrates if you have enough good shoots. And proper illumination. Low sugar may help to rooting if you light is not enough. But it is not necessary.
Pure agar is rather neutral.
My best wishes!
Hi Pim,
I agreed with Jullien Marc. I have worked with photoautotrophic micropropagation for several plant species for almost twenty years. I cultured explants with leaves on medium without sucrose and vitamins in ventilated vessels under light. In vitro plants grew well with big leaves and more lateral roots.
Yes, Plants in tissue culture use agar as an energy source when sugar is absent from the medium .
Madhukar Baburao Deshmukh, do you have any reference for your statement?
Hi, you bigan your work with adding sucrose and your shoots grew and formed leaves which can be promoted to do its job in formation carbohydrates specially when it suffer from lack of carbo-sorce in medium, and tis is a method to pre-acclimatzation and stimulation of active photosynthesis
Hi dear Ebtsam Hamz, actually as far i know Agar is nothing but solidifying agent which provide only support to the new emerging plantlets. So Agar is not alternative to sucrose in culture media. But if you grow shoots of the plantlets under media containing sucrose then after during subculture you avoid sucrose, Then i think its ok for root growth of that plantlets. Because without sucrose plants feel become stress and due to lack of energy it tries to recover the energy at any cost. So plantlet produce huge root for uptake nutrient and shoot occurs photosynthesis (light and dark phage) for producing sufficient energy for that plant.
This question raised more than 2 years ago. If Pim is still following this question, I would like to know his opinion.
I wonder if a quite simple experiment was ever done, by comparing zero, low and normal doses... Would that settles this question?
Luis Carlos da Silva Ramos Zero, low and normal doses of what? You don't mean agar? The question was: is it possible to use agar as sole energy source, without sugars (or other usable carbohydrates?...)
Luis Carlos da Silva Ramos I think it would be more a question of the timing. Immediately after insertion of the pieces from the mother plant, mostly the nodia, into the agar medium it will need a additional carbon source. Later, after developing and growth of green plant parts it would be able to synthesis carbohydrates by itselfs. But would it be necessary to make investigation with several doses of carbohydrates? Mostly one works with certain reciep for medias for plant tissue culteres. These recieps already are the results og many experiments with different constituent and of several concentrations or doses.
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