SummaryInventors in the field of mechanical and electronic engineering can access multitudes of components and, thanks to standardization, parts from different manufacturers can be used in combination with each other. The introduction of BioBrick standards for the assembly of characterized DNA sequences was a landmark in microbial engineering, shaping the field of synthetic biology. Here, we describe a standard for Type IIS restriction endonuclease-mediated assembly, defining a common syntax of 12 fusion sites to enable the facile assembly of eukaryotic transcriptional units. This standard has been developed and agreed by representatives and leaders of the international plant science and synthetic biology communities, including inventors, developers and adopters of Type IIS cloning methods. Our vision is of an extensive catalogue of standardized, characterized DNA parts that will accelerate plant bioengineering.

A major challenge in biology is to understand how buds comprising a few cells can give rise to complex plant and animal appendages like leaves or limbs. We address this problem through a combination of time-lapse imaging, clonal analysis, and computational modeling. We arrive at a model that shows how leaf shape can arise through feedback between early patterns of oriented growth and tissue deformation. Experimental tests through partial leaf ablation support this model and allow reevaluation of previous experimental studies. Our model allows a range of observed leaf shapes to be generated and predicts observed clone patterns in different species. Thus, our experimentally validated model may underlie the development and evolution of diverse organ shapes.

A key challenge in evolutionary biology is to understand how new morphologies can arise through changes in gene regulatory networks. For example, floral asymmetry is thought to have evolved many times independently from a radially symmetrical ancestral condition, yet the molecular changes underlying this innovation are unknown. Here, we address this problem by investigating the action of a key regulator of floral asymmetry, CYCLOIDEA (CYC), in species with asymmetric and symmetric flowers. We show that CYC encodes a DNA-binding protein that recognises sites in a downstream target gene RADIALIS (RAD)in Antirrhinum. The interaction between CYC and RADcan be reconstituted in Arabidopsis, which has radially symmetrical flowers. Overexpression of CYC in Arabidopsis modifies petal and leaf development, through changes in cell proliferation and expansion at various stages of development. This indicates that developmental target processes are influenced by CYC in Arabidopsis, similar to the situation in Antirrhinum. However, endogenous RAD-like genes are not activated by CYC in Arabidopsis, suggesting that co-option of RAD may have occurred specifically in the Antirrhinum lineage. Taken together, our results indicate that floral asymmetry may have arisen through evolutionary tinkering with the strengths and pattern of connections at several points in a gene regulatory network.