Control of plant development by reactive oxygen species.

Reactive oxygen species (ROS) are emerging as important regulators of plant development. There is now abundant evidence that ROS play roles in cell growth and that spatial regulation of ROS production is an important factor controlling plant form. Here we will review evidence that supports a role for ROS in development, but first we will define what we mean by development. The body of the vascular plant sporophyte (diploid life cycle stage) is derived from meristems and much of the action of development occurs where organs are formed in and around meristems (Martienssen and Dolan, 1998). Organogenesis, the development of organs, involves an early patterning stage that roughs out boundaries where the organswill form. Within these boundaries, groups of founder cells divide and growth occurs, leading to the formation of structures containing arrays of differentiated cells. There are twomajor contributors to growth: First, there is cell division, which increases the number of cells in an organ; second, there is expansion of those cells. The huge increase in volume in plant cells as they transit from the founder population in and around meristems to the differentiated cells of the mature organ means that cell growth is an important component of plant development (Sugimoto-Shirasu and Roberts, 2003). Recent discoveries suggest that ROS may control development through their role in regulating cell growth.