An international group of scientists, led by the Centre for Plant Integrative Biology at the University of Nottingham, has shed light on how a plant hormone is crucial in controlling the growth of plant roots.

Plant growth is driven by an increase in two factors - the number of cells, and their size. It is already known that the plant hormone gibberellin controls how root cells elongate as the root grows in the model plant Arabidopsis thaliana.

Now a paper appearing in Current Biology describes for the first time how this hormone also regulates the number of cells in the root in order to control root growth.

Gibberellin normally acts by signalling the removal of proteins which repress growth, and so promotes root cell production. The new research shows that mutant plants that do not produce gibberellin are unable to increase their cell production rate and the size of the root meristem, the zone of cell proliferation.

This research was headed by Dr Susana Ubeda-Tomás and Professor Malcolm Bennett of the Centre for Plant Integrative Biology, in collaboration with scientists in Nottingham, Cambridge, Edinburgh, Spain, Belgium and Sweden.

Professor Malcolm Bennett, biology director for the Centre for Plant Integrative Biology, said: “We have shown that gibberellin plays a crucial role in controlling the size of the root meristem, and that it is the endodermis which sets the pace for expansion rates in the other tissues.

“Understanding precisely how hormones regulate plant growth is one of the key areas of fundamental plant biology which will underpin crop improvements in the future.”

The Centre for Plant Integrative Biology is funded by the Systems Biology joint initiative of BBSRC and EPSRC, which has provided £27 million for six specialised centres across the UK.

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