RUB Researchers Reveal Molecular Basis of Plant's Shade Avoidance Syndrome

When smaller plants lose the battle during competitiveness for light due to larger plants, they counteract by elongating their shoot and stretching their leaves towards the sun. This reaction is called shade avoidance syndrome. Since the molecular basis for this syndrome is still unclear, Stephan Pollman of the Ruhr University in Bochum (RUB) and colleagues identified a regulation pathway. PIN-FORMED 3 or PIN3, a transport protein, enables the buildup of growth hormone auxin, which is involved in this adaptation process.

When the ratio between red to far red is low (which occurs during low light conditions) PIN3 accumulates on the lateral endodermal cell walls. This would eventually lead to auxin flow towards the epidermal cell layers, which are involved in the elongation of the shoot.

To verify the auxin content of plants under sunlight and plants under shade, the researchers used mass spectrometry. They compared the amount of auxin between a wild-type Arabidopsis plants and genetically engineered plants, which cannot develop PIN3. Shade avoidance syndrome was not observed in the GE plants.

The complete article published by the PNAS is available at http://www.pnas.org/content/early/2010/12/08/1013457108.full.pdf+html?sid=2bce3a8d-d5d9-487e-8695-e14470cb45e5 http://aktuell.ruhr-uni-bochum.de/pm2010/pm00434.html.en.