Cell cycle : the key to plant growth control?
Faculty of Sciences. Biology
Trends in plant science. - London
, p. 154-158
Experimental evidence on the role of the cell cycle in plant growth regulation does not exclusively fit the cellular (division drives growth) or the organismal perspective (division merely accompanies growth). Here we present a broader, integrated concept of plant growth regulatory interactions, which accommodates experimental results gathered to date. This model can serve as a basis for future research, and prompts experimental approaches to encompass both measurements of cell growth and division parameters. Over the past 30 years, the molecular basis of cell cycle regulation has been uncovered, primarily using yeast as a model system. The basic mechanism is conserved between all eukaryotes, and most of its components were identified in plants in the early 1990s . Now that transgenic plants with altered expression of various cell cycle genes have been created, we can start to answer longstanding fundamental questions about plant growth. When addressing the function of cell division in the growth process of a multicellular organ(ism), the role of individual cells is a controversial issue. Two opposing views have been proposed : the cell theory and the organismal theory. The cell theory considers cells as elemental building blocks of the organism, and growth therefore results from an increase in cell number. According to the organismal theory, cells are merely compartments of organismal space, cell division being a consequence rather than the cause of growth. In other words, the production of cellular compartments is imposed by the growth of the organ as a whole rather than the inverse. The most widely cited support for this view is the observation that in gamma-irradiated seedlings, coordinated growth continues in the absence of division .