13 Root Development in Arabidopsis

Abstract

The Arabidopsis plant, like most angiosperms, produces an extensive root system designed to function in the anchorage of the plant and absorption of water and mineral ions. The development of the plant root system is relatively easy to study, despite the fact that roots are generally subterranean organs. Several properties of roots make them amenable to developmental studies: (1) The root apical meristem is accessible and not enclosed by developing organs or primordia; (2) the root is free of pigments and therefore essentially transparent; (3) there are relatively few differentiated cell types in roots; (4) root morphogenesis in many plants occurs in a continuous and relatively uniform fashion without significant developmental transitions; and (5) cell files are easy to observe in longitudinal sections and their origin can be traced back to the apical meristem. Our understanding of root morphology and development in Arabidopsis has come largely from studies of the seedling root system. The small size of the Arabidopsis seedling and its ability to be grown aseptically under defined conditions facilitates morphological, physiological, and genetic analyses. The genetic studies of root development in Arabidopsis have been particularly illuminating and have led to the isolation of many root developmental mutants. In this chapter, we review our current understanding of root development in Arabidopsis by describing research on roots of Arabidopsis as well as roots of other plants, where appropriate. For readers interested in a detailed discussion of physiological or functional aspects of roots, reviews can be found in Torrey and Clarkson...