Pausing growth

Plant & zo

The science of plants and more

Pausing growth

Just like ours, the environment of plants is in flux, changing constantly. There can be a drought, or a shortage of nutrients. To survive, plants adjust their growth. By shortage of water a plant will grow little to none. Only to start growing again after rain has fallen. For long it was not known how a plant managed to do this, but now researchers have discovered its secret.

Plants grow from growth regions. With only the cells in those growth regions dividing. TOR is one of the proteins that is promoting growth from these regions. TOR is turned on in every dividing cell. Is TOR turned off, then the cell is no longer part of the growth region. During stress, like water shortage, the number of cells in the growth regions declines. TOR is turned on in fewer cells.

Temporally release of the TOR-off switch pauses growth during stressful periods

Researchers from Portugal and Belgium studied how drought can turn-off TOR. They focussed on the effect of the drought-manager ABA has on a protein that can switch off TOR. During optimal conditions this protein is located in the nucleus of the cell. Preventing the TOR-off switch reaching TOR.  But, as the researchers noticed, ABA frees the TOR-off switch from the nucleus. Now it can turn off TOR.

When rain is making an end of the drought, the drought-manager leaves. Its job is finished. This forces the TOR-off switch to stay in the nucleus again. Keeping TOR on, the number of cells in the growth region increases, and the plant starts growing again. The temporally release of the TOR-off switch pauses growth during stressful periods. It enables the drought-manager to help plants better cope with stress.


Borja Belda-Palazóna, Mónica Costaa, Tom Beeckman, Filip Rollandd, and Elena Baena-González (2022) ABA represses TOR and root meristem activity through nuclear exit of the SnRK1 kinase. PNAS 119 (28) e2204862119

Published by Femke de Jong

A plant scientist who wants to let people know more about the wonders of plant science. Follow me at @plantandzo

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