Plant & zo
The science of plants and more
Controlled orientation
Sometimes, when you are studying something in more detail, it turns out to be working a little different than you first imagined it. This is shown by American researchers in Nature for the orientation of cell divisions of root cells.
The final form of an organism is the result of a whole bunch of precise cell divisions. In plant roots the orientation of the cell division determines if there will be more cells of the same cell type, or that that there will be an extra cell type. For the precursor cell of the cortex and epidermis cell layers it was long thought that just the presence of the gene-on switchers SHR and SCR would be enough for the extra cell type oriented cell division. Now the researchers show that it works a little different.
The researchers decided to study in more detail how SHR and SCR influence cell division orientation. Observing the levels of SHR and SCR in the roots over 48 hours. Surprisingly the levels of SHR and SCR was fluctuating more than expected.
Higher abundance if SHR and SCR early in the cell cycle results in the extra cell layer type of cell divisions
Following this the researchers developed a new model that fitted better with the newly obtained observations. The final model that they got suggested the importance of a slightly higher abundance of SHR and SCR at the start of the cell cycle for extra cell type oriented cell divisions.
The researchers tested if this was indeed the case. First they temporally stopped cell divisions at the start of the cell cycle. When they re-started the cell divisions in the presence of SHR and SCR, then all the cells divided in an extra cell type oriented way. But had they stopped the cell divisions at a later point in the cell cycle, then, even in presence of SCR and SHR, all cells divided in a more cells of the same cell type oriented way.
Showing that even when you think you know how something works. It still might be worthwhile to study something in more detail. You might discover that things are working in a slightly different way.
Literature
Winter, C.M., Szekely, P., Popov, V. et al. SHR and SCR coordinate root patterning and growth early in the cell cycle. Nature (2024). https://doi.org/10.1038/s41586-023-06971-z
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