Scientists have discovered an unusual and novel role for the plant hormone auxin in the development of the female organs of the flower.
As they develop, the structures of many organisms begin as a ball of similar cells with radial symmetry, which then develop bilateral symmetry as the cells differentiate and the organ matures. Until now, evidence of post-embryonic organ development in the opposite direction – from a bilaterally symmetrical form to a radial one – has only been observed in the sea urchin.
However, plant scientists Professor Lars Østergaard and Laila Moubayidin from the John Innes Centre in Norwich have discovered that tissue at the tip of the gynoecium – the structure that forms the female reproductive organ of a flower – also goes through a bilateral to radial transition. The resulting radial structure makes up the style of the gynoecium. Using the weed Arabidopsis thaliana in their experiments, the researchers found this unusual transition to be controlled by two genes directly affecting auxin distribution.