During embryogenesis a single cell gives rise to a func-tional multicellular organism. In higher plants, as in many other multicellular systems, essential architectural fea-tures, such as body axes and major tissue layers are es-tablished early in embryogenesis and serve as a positional framework for subsequent pattern elaboration. In Arabi-dopsis, the apical- basal axis and the radial pattern of tis-sues wrapped around it are already recognizable in young embryos of only about a hundred cells in size. This early axial pattern seems to provide a coordinate system for the embryonic initiation of shoot and root. Findings from genetic studies in Arabidopsis are revealing molecular mechanisms underlying the initial establishment of the axial core pattern and its subsequent elaboration into functional shoots and roots. The genetic programs oper-ating in the early embryo organize functional cell patterns rapidly and reproducibly from minimal cell numbers. Un-derstanding their molecular details could therefore great-ly expand our ability to generate plant body pat- terns de novo, with important implications for plant breeding and biotechnology.

Arnaud Capron, Steven Chatfield, Nicholas Provart and Thomas Berlethan

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