Each growth centre cell type its own complex
Plants regulate their cell divisions very strict. There are lots of proteins involved in this regulation. Now German and Dutch researchers show in EMBO reports the interaction of those proteins in root growth centre.
In plants cell divisions mainly take place in growth centres. These are located at the tips of the stems and roots. The cells in the middle divide extremely slowly, while the surrounding cells divide quicker. But as soon as the cells are pushed out of the growth centre cell division stops. The researchers decided to find out how a cell knows how fast it needs to divide.
The researchers studied the three main players, the gene regulators: WOX5, PLT3, and BRAVO. All three each independently affect cell divisions in the root growth centre. And for WOX5 and PLT3, and WOX5 and BRAVO it is also known that they can interact. But which specific cells in the growth centre those proteins exactly influence was not exactly clear.
WOX5, PLT3, and BRAVO work together to regulate cell divisions in the growth centre
To get a better view of this the researchers studied the abundance of each of the three proteins in the growth centre. They were present in all the different cells of the growth centre, but in different abundancies. For example, WOX5 has a big preference for the slowly dividing inner cells of the growth centre.
Subsequently the researchers analysed if the three proteins could interact with each other. Firstly, they checked if BRAVO and PLT3 could interact. Which they could, even more tightly than PLT3 to WOX5 or WOX5 to BRAVO. Then they tested if those three proteins could form a complex which indeed they could.
All the collected data the researchers then brought together in a model. From this it became clear that in the inner slowly dividing proteins, there the three main players mostly interacted with each other, although there is also lots of single WOX5.
Each cell type within the growth centre has its own composition of the three main players
In the cells that form the precursors for the root cells, there are also lots of complexes with the three main players. With in addition lots of single BRAVO proteins. At the other side, the cells that form the precursors for the root cap cells, they contain mainly complexes with WOX5 and PLT3. But there is also lost of single PLT3.
In this way each cell type of the growth centre has its own specific ratio and complex composition of the three main players that regulate the growth centre. In absence of one cell division in the whole growth centre is disturbed.
Literature
Vivien I Strotmann, Monica L García-Gómez, and Yvonne Stahl. (2025) Root stem cell homeostasis in Arabidopsis involves cell-type specific transcription factor complexes. EMBO reports https://doi.org/10.1038/s44319-025-00422-8
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