I am wondering whether it is possible for two callus to be combined into one... both between genetically similar plants and genetically different plants.
i think its not possible, because callus is a mass of undifferentiated cells. But you can separate some cells from both the callus and then you could do protoplast culture, howeve, it’s therotica
Munagala Sai Kiran Thanks for the answer: I have some more follow up questions!
What will happen if I force them to be near each other? Or what if I damage part of both callus and put them together... this may sound stupid but I am very curious. Merging two calluses is kind of like grafting isn't it? The reason grafting doesn't work on monocot is because there is no Cambium tissue to regenerate... Callus, however, are, just like you said, a mass of undifferentiated cell. The merging of the two calluses shouldn't be a problem then? Though I am not sure about plasmodesmata formation and its implication.
Settanan Plangsiri I did hear that a plant could derive from two or more (?) cells and become chimeric. For example, one cell is transformed and one cell is not transformed. These 2 cells can be from 2 distinct calli. But, I have not encountered a literature reporting and discussing this in detail. I am interested to see a scientific report about that.
Dear friend, if you dealing with genetic transformation (in case) using Agrobacterium, you ll avoid doing it owing to the concept of transformation event. Even it sounds illogical while performing conventional in vitro experiments.
Settanan Plangsiri Callus is not simply "a mass of undifferentiated cells", that is a quite outdated definition. Regeneration from callus occurs from groups of cells that form a primordium which is similar to a lateral root primordium. This primordium is pluripotent, so its default option is to differentiate into a root, but in the in vitro culture you can force it to differentiate into a shoot by adding cytokinin.
Now, in order to get a hymeric shoot as in grafting, you would probably need to obtain a hymeric primordium, because I doubt that you can force two primordia to merge into one. But even obtaining a hymeric primordium would be probably very difficult to do, because a primordium forms from a group of cells that are already placed very close to each other and are derived from a single cell. In case of a hymeric transformation, you start from the cells that are close together, but one has been transformed and the other has not. To obtain a hymeric primordium starting from two completely separated calluses, sounds impossible to me. Maybe there is a chemical way to do that, but if there is, I haven't heard about it.
I'm attaching for you an article on the transdifferentiation of pluripotent primordia. It describes an experiment in a direct regeneration system (without callus) but basic principles are similar, as in the callus tissue you still need this kind of primordia to obtain regeneration. I hope you will find this article useful.
Martin Raspor
You mentioned "Regeneration from callus occurs from groups of cells that form a primordium which is similar to a lateral root primordium." Do you happen to know some papers or reviews reviewing this topic? I would like to learn more. Thanks.
Yuan-Yeu Yau Take a look at the paper by O. Rosspopoff et al. (2017) that I attached in my reply to Settanan. (DOI: 10.1242/dev.142570)
Another important work is by Kareem et al. 2015 (10.1016/j.cub.2015.02.022)
And you might want to take a look at one of these review papers:
Radhakrishnan et al. 2018 Article Shoot regeneration: a journey from acquisition of competence...
Sugimoto et al. 2019
Article To regenerate or not to regenerate: factors that drive plant...
and Ikeuchi et al. 2019
Article Molecular Mechanisms of Plant Regeneration
Martin Raspor Thanks for such a well explained answer, Martin!!
I have some further question... I've been searching the word hymeric primordial on Google and couldn't really find anything on it. Do you have any article that explain deeper into hymeric primordial?
Second question: Plant recognize and communicate with their neighbor cells through plasmodesmata right? So what if I breakdown their cell walls into protoplast and form secondary plasmodesmata between the two allowing the two plants to communicate to each other, would the merge be possible that way?
Settanan Plangsiri You didn't find anything about hymeric primordia because hymeric primordia probably do not exist. As I said, I doubt that anyone has done anything like that.
If there is any chance to obtain something like that, I think that yes, starting from a protoplast culture would be the most logical first step. However... Primordium formation is a very complex and highly organized process and it is not always easy to induce it even in normal plant explants. In your case, you would have to force your cells to do two complicated things at the same time: (1) get together and merge into a tissue of hybrid origin; (2) get into the genetic programmes of primordium initiation. I'm not saying that doing both things at the same time is theoretically impossible, but let's say that in the best scenario it would be probably very complicated to do, and would require LOTS of experiments, probably a well-funded research project.
I suggest that you get familiar with the paper I sent to you and with related research (take a look also at the publications I recommended to Yuan) and get familiar with the processes related to the initiation of lateral root primordia. It is a good start for whatever further research you are going to do related to shoot regeneration.