Leaves come in all shapes and sizes and scientists have discovered simple rules that control leaf shape during growth.

Using this ‘recipe’, they have developed the first computer model able to accurately emulate leaf growth from a bud.

“A bud does not grow in all directions at the same rate,” said Samantha Fox from the John Innes Centre on Norwich Research Park. “Otherwise leaves would be domed like a bud, not flat with a pointed tip.”

By creating a computer model to grow a virtual leaf, the BBSRC-funded scientists managed to discover simple rules of leaf growth.

Similar to the way a compass works, plant cells have an inbuilt orientation system. Instead of a magnetic field, the cells have molecular signals to guide the axis on which they grow. As plant tissues deform during growth, the orientation and axis changes.

The molecular signals become patterned from an early stage within the bud, helping the leaf shape to emerge.

The researchers filmed a growing Arabidopsis leaf, a relative of oil seed rape, to help create a model which could simulate the growing process. They were able to film individual cells and track them as the plant grew.

It was also important to unpick the workings behind the visual changes and to test them in normal and mutant plants.

“The model is not just based on drawings of leaf shape at different stages,” said Professor Enrico Coen. “To accurately recreate dynamic growth from bud to leaf, we had to establish the mathematical rules governing how leaf shapes are formed.”

With this knowledge programmed into the model, developed in collaboration with Professor Andrew Bangham’s team at the University of East Anglia, it can run independently to build a virtual but realistic leaf.

Professor Douglas Kell, Chief Executive of BBSRC said:  “This exciting research highlights the potential of using computer and mathematical models for biological research to help us tackle complex questions and make predictions for the future. Computational modelling can give us a deeper and more rapid understanding of the biological systems that are vital to life on earth.”

The model could now be used to help identify the genes that control leaf shape and whether different genes are behind different shapes.

“This simple model could account for the basic development and growth of all leaf shapes,” said Fox. “The more we understand about how plants grow, the better we can prepare for our future – providing food, fuel and preserving diversity.”