GDP-L-fucose is required for boundary definition in plants.

The CUP-SHAPED COTYLEDON (CUC) transcription factors control plant boundary formation, thus allowing the emergence of novel growth axes. While the developmental roles of the CUC genes in different organs and across species are well characterized, upstream and downstream events that contribute to their function are still poorly understood. To identify new players in this network, we performed a suppressor screen of CUC2g-m4, a line overexpressing CUC2 that has highly serrated leaves.

Divide et impera: boundaries shape the plant body and initiate new meristems.

485 I. 485 II. 486 III.

A conserved role for CUP-SHAPED COTYLEDON genes during ovule development.

The evolution of plant reproductive strategies has led to a remarkable diversity of structures, especially within the flower, a structure characteristic of the angiosperms. In flowering plants, sexual reproduction depends notably on the development of the gynoecium that produces and protects the ovules. In Arabidopsis thaliana, ovule initiation is promoted by the concerted action of auxin with CUC1 (CUP-SHAPED COTYLEDON1) and CUC2, two genes that encode transcription factors of the NAC family (NAM/ATAF1,2/CUC).

Lateral suppressor and Goblet act in hierarchical order to regulate ectopic meristem formation at the base of tomato leaflets.

In seed plants, new axes of growth are established by the formation of meristems, groups of pluripotent cells that maintain themselves and initiate the formation of lateral organs. After embryonic development, secondary shoot meristems form in the boundary zones between the shoot apical meristem and leaf primordia, the leaf axils. In addition, many plant species develop ectopic meristems at different positions of the plant body.

Model for the regulation of Arabidopsis thaliana leaf margin development.

Biological shapes are often produced by the iterative generation of repeated units. The mechanistic basis of such iteration is an area of intense investigation. Leaf development in the model plant Arabidopsis is one such example where the repeated generation of leaf margin protrusions, termed serrations, is a key feature of final shape.

Evolution and diverse roles of the CUP-SHAPED COTYLEDON genes in Arabidopsis leaf development.

CUP-SHAPED COTYLEDON2 (CUC2) and the interacting microRNA miR164 regulate leaf margin dissection. Here, we further investigate the evolution and the specific roles of the CUC1 to CUC3 genes during Arabidopsis thaliana leaf serration. We show that CUC2 is essential for dissecting the leaves of a wide range of lobed/serrated Arabidopsis lines.

Leaving the meristem behind: the genetic and molecular control of leaf patterning and morphogenesis.

Leaves, which play an essential role in plant photosynthesis, share common features such as being flat structures, but also show an impressive variability in their sizes and shapes. Following its initiation in the meristems, leaf development is patterned along three polarization axes to establish its basic architecture. This process is further complicated in the case of compound leaves with the formation of new growth axes.

Leaf development: what it needs to be complex.

Formation of dissected compound leaves involves the transient maintenance of an indeterminate environment and the generation of new growth axes that will generate leaflets. Recent work has revealed additional multi-layered mechanisms controlling the activities of the KNOXI homeodomains factors that play a prominent role in the control of indeterminacy associated with compound leaf development. Patterning and individualisation of the leaflets has been shown to involve gradients of the phytohormone auxin and the contribution of the NAM/CUC3 boundary genes.