Dec. 31, 2008 Plants come in all shapes and sizes, from grand
Redwood trees to the common Snowdrop. Although we cannot see
them, under the ground plants rely on a complex network of
roots. What determines the pattern of root growth has been a
mystery, but a new paper shows that the shape of the existing
root can determine how further roots branch from it – because
shape determines hormone concentration. The work also suggests
that the root-patterning system shares a deep evolutionary
relationship to the patterning system of plant shoots, something
that had not been realized previously. The paper, by Laskowski,
Grieneisen, Hofhuis, et al, explores the architecture of the
root system of the model organism Arabidopsis thaliana, a plant
with the unusual common name "mouse-ear cress." The authors show
that the curve of the root is key in provoking new growth. They
used computational modeling of the transport of a well-known
plant hormone, auxin, and by following the diffusion of this
hormone they reveal that its a