Balancing reactive oxygen species for a better root boundary
Last updated: 8 Dec, 2016
Plants adjust the pattern of their roots to maximise nutrient and water uptake from the soil. A new study published in New Phytologist reveals how root growth is controlled by setting the boundaries of new roots using reactive oxygen species (ROS), once thought to be the toxic by-products of cells.
MYB36 is expressed in the cells surrounding the developing lateral root, defining the boundary between the parent and progeny root tissues (blue: MYB36-GUS). Credit: Fernández-Marcos et al. (2016).
Throughout their lifetime, plants produce new root branches (lateral roots) to explore new parts of the soil and help to anchor themselves into the soil. Researchers in Spain and the USA discovered that a gene, MYB36, was responsible for promoting the growth of new lateral roots. In plants lacking MYB36, the early cell divisions at the start of lateral root development take place as normal, but they stop growing before the lateral root emerges from its parent.
MYB36 is produced by boundary cells surrounding the developing lateral root, where it was found to control the expression of a subset of ROS-regulating enzymes called peroxidases. These enzymes alter the balance of ROS in the boundary cells, restricting their cell division and forcing the lateral root to grow outwards. The researchers confirmed this by removing ROS from the plants; in normal plants, this removal of ROS caused the lateral roots to stop developing, while in the plants lacking MYB36, the roots were able to grow normally in the absence of ROS. This showed that MYB36 acts to maintain the correct balance of ROS and set up a boundary between the parent and lateral root, which is required for later outward growth.
MYB36 has previously been shown to control the development of the primary (parent) root, and this new study reveals its function in a similar mechanism in root branching, highlighting the importance of defining developmental boundaries between cell division and later specialisation.
Read the paper: Fernández-Marcos, M., Desvoyes, B., Manzano, C., Liberman, L. M., Benfey, P. N., del Pozo, J. C. and Gutierrez, C. (2017) Control of Arabidopsis lateral root primordium boundaries by MYB36. New Phytologist, 213: 105–112. doi: 10.1111/nph.14304
Read the blog post: A radical role in root development