Control mechanism for plant root size-control elucidated

August 15, 2014

The mechanism of how the number of plant cells increases at root tips to form vascular bundles has been elucidated for the first time by a joint research team from the University of Tokyo and the RIKEN Center for Sustainable Resource Science (CSRS). Roots of dicotyledonous plants are known to grow larger through increasing the number of vascular bundle cells, helping to carry water and nutrients to all parts of a plant. Prior to this research, it was not clear how these cells increased.

Using the model plant Arabidopsis, the research collaborators discovered that LHW and T5L1 genes controlling the shape of vascular bundles in plant roots are responsible for inducing expression of genes related to synthesis of the hormone cytokinin. This induction leads to increased cytokinin in vascular bundles, which in turn contributes to an increased number of bundles. The end result is larger root size.

In addition to responsibility for cytokinin synthesis, the team discovered that LHW and T5L1 also control gene expression for cytokinin signaling, with genes acting as a switch to control activation of cytokinesis in vascular bundles by regulating and balancing both cytokinin synthesis and signaling.

These findings could potentially guide the way to creation of stout and sturdy roots right from the onset of plant growth, leading to improved crop productivity.


Original article
Current Biology doi: 10.1016/j.cub.2014.07.050
K. Ohashi-Ito, M. Saegusa, K. Iwamoto, Y. Oda, H. Katayama, M. Kojima, H. Sakakibara, H. Fukuda,
"A bHLH complex activates vascular cell division via cytokinin action in root apical meristem".

Hitoshi Sakakibara
Group Director
Plant Productivity Systems Research Group