Reactive oxygen species as important regulators of cell division

Currently, the role of reactive oxygen species (ROS) in plant growth is a topic of interest. In this study, we discuss the role of ROS in cell division. We analyzed ROS impact on the stiffness of plant cell walls and whether ROS play an important role in Brassica napus ability to adapt to cold stress. Cultivated sterile seedlings and calli of cold-tolerant cultivar 16NTS309 were subjected to cold stress at 25{degrees}C and 4{degrees}C, respectively. Under normal conditions, O2.- mainly accumulated in the leaf edges, shoot apical meristem, leaf primordia, root tips, lateral root primordia, calli of meristematic nodular tissues, cambia, vascular bundles and root primordia, which are characterized by high division rates. After exposure to cold stress, the malondialdehyde and ROS (O2.-) contents in roots, stems and leaves of cultivar 16NTS309 were significantly higher than under non-cold conditions (P < 0.05). ROS (O2.-) were not only distributed in these zones, but also in other cells, at higher levels than under normal conditions. A strong ROS-based staining appeared in the cell wall. The results support a dual role for apoplastic ROS, in which they have direct effects on the stiffness of the cell wall, because ROS cleave cell-wall, and act as wall loosening agents, thereby either promoting or restricting cellular division. This promotes the appearance of new shoots and a strong root system, allowing plants to adapt to cold stress.