Its a Matter of Size: Intracellular Control of Plant Organ SIze

Although the environment plays a major role in determining plant growth patterns, intrinsic size of certain plant organs, like flowers and leaves, appears to be controlled by an internal mechanism. The mechanism however, remains, elusive. Recently, scientists from the University of Freiburg in Germany and the John Innes Centre in Norwich UK have discovered that cells at the margins of leaves and petals play a particularly important role in setting their size.

The cells secrete a mobile growth signal that keeps the cell dividing. The mobile element was identified to be Arabidopsis cytochrome P450 KLUH. Mutants that lack the klu gene produced smaller organs because of premature arrest of cell division and proliferation. Overexpression of the gene resulted to plants with larger organs containing more cells. The researchers hypothesized that since the signals are secreted in the margins, it gets diluted as the petals or leaves grow. Once the signal falls below a certain threshold concentration, the organs cease from growing.

The interesting aspect of the discovery is that KLU does not appear to regulate the levels of any known plant hormone. Manipulation of the mobile growth element may result to plants with larger leaves or increased biomass, which may aid in biofuel production.

The abstract of the paper published by Developmental Cell is available at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WW3-4R8G8V2-F&_user=677719&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000036823&_version=1&
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