How to grow a new plant from a single differentiated cell?
Researchers will benefit from a new culture procedure created by RIKEN scientists as they explore the mechanism by which some single plant cells can regenerate into complete plants.
Some plants naturally have the amazing capacity to generate an entirely new plant from a single cell that neither an egg nor a sperm. But scientists can modify specific plant cell types so that they can develop into other cell types and eventually an entire plant.
However, because they don’t have defined protocols for managing the process, they only occasionally succeed in doing this. Such procedures may improve our knowledge of the molecular mechanisms underlying the development of plants from isolated cells, which has significance for plant breeding.
The RIKEN Center for Sustainable Resource Science’s Keiko Sugimoto and colleagues have now developed a procedure that reprograms “protoplast” cells to re-enter the cell cycle and start cell division.
The formation of protoplasts, which are similar to stem cells in humans, requires the removal of the cell wall from specific isolated plant cells. Protoplasts are not naturally present in plants. The new method successfully reprogrammed leaf mesophyll cell-derived protoplasts to grow into new plant shoots.
Protoplasts are extremely sensitive because they lack cell walls; they require a certain amount of stress to start reprogramming, but if you do them too much harm, they will die. This makes it challenging to get the procedure just right. We can start to understand the underlying molecular mechanisms of this process because our technology successfully induced reprogramming in 2-5% of protoplasts.
The research team identified auxin as a key player in the activation of cell division. The fact that protoplasts need to produce new auxin to restart cell division, while being cultivated in a medium containing synthetic auxin, was a significant finding and the largest surprise to the team, according to Sugimoto.
Additionally, when auxin is produced in protoplasts, the researchers were able to pinpoint some of the chemicals and genes that are involved in the beginning of cell division.
However, many questions remain. How closely, for instance, is auxin synthesis related to protoplast reprogramming? What other molecular processes are active here? And what causes a mature cell to change from an isolated state into a state where it can regenerate entire plants with less differentiation?
By finding the answers to these inquiries, Sugimoto asserts that they might be able to regenerate transgene-free, genome-edited plants from protoplasts.
Additionally, animals may be affected. Sugimoto claims that most animals are unable to regenerate an entire body from a single differentiated cell but plants are rather adept at doing so. Researchers anticipate that knowing how plant cells function will assist explain why animal cells are unable to do so.
Sources:
Yuki Sakamoto et al, Transcriptional activation of auxin biosynthesis drives developmental reprogramming of differentiated cells, The Plant Cell (2022). DOI: 10.1093/plcell/koac218
https://phys.org/news/2022-11-recipe-differentiated-cell.html
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