1 Institute of Molecular Plant Science, School of Biological Sciences, University of Edinburgh, Daniel Rutherford Building, King's Buildings, Edinburgh EH9 3JH, UK
2 Present address:
ICMB, University of Edinburgh, Daniel Rutherford Building, Edinburgh EH9 3JH, UK [email protected]
Abstract Plant growth is mediated by three fundamental processes: cell growth, division, and expansion. The mechanistic analysis of their contributions are complicated by the observation that the balance of their contributions to organ growth are not hard-wired. Reduced cell proliferation, irrespective of whether this is caused by decreased cell growth or diminished cell division, can be, at least partially, compensated for by increased cell expansion. It is therefore argued that for a functional understanding of how gene regulatory networks control growth of the plant body, it is essential that all cellular parameters contributing to organ growth are quantified in concert. Plant growth behavior is exquisitely responsive to environmental change. Cell growth, division, and expansion, in aggregate, are promoted by nutrient availability and inhibited by abiotic stress. Recent studies that address how light intensity, CO2 concentration, water activity, and temperature have complex effects on proliferation, cell expansion, and endoreplication that affect leaf organ growth are reviewed. Root growth rates and patterns are also very sensitive to mineral nutrient concentration and distribution. The mechanistic basis of plant organ growth still remains unknown; but such knowledge is critical for rational approaches to manipulate plant growth. Critical steps towards this goal are discussed.
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