The coordination of cellular behaviour that results in development involves the synchronization of many distinct patterning processes. A prime example of coordination at different levels is the process of lateral organ development. Firstly, a positioning system ensures that new organs initiate at the right locations. Secondly, gene expression must be patterned so as to define the different tissue types correctly. Lastly, specific patterns of localized growth must occur such that the organ develops to the correct size and morphology. How are these distinct processes regulated and what signals coordinate their patterning?By building on my recent work, this proposal aims, for the first time, to build an integrated understanding of how these distinct patterning processes arise and coordinate with one another, in the model plant species Arabidopsis thaliana. The proposal utilizes and extends the multispectral live-imaging techniques I pioneered as a postdoc and combines this approach with state-of-the-art transcriptomics and perturbation methods. Specifically, I aim to understand the regulatory links that coordinate dorsoventral patterning, cell polarity and morphogenesis at the shoot apical meristem (SAM) and during lateral organ development.