The position of leaves and flowers along the stem axis generates a specific pattern, known as phyllotaxis. A growing body of evidence emerging from recent computational modeling and experimental studies suggests that regulators controlling phyllotaxis are chemical, e.g. the plant growth hormone auxin and its dynamic accumulation pattern by polar auxin transport, and physical, e.g. mechanical properties of the cell. Here we present comprehensive views on how chemical and physical properties of cells regulate the pattern of leaf initiation. We further compare different computational modeling studies to understand their scope in reproducing the observed patterns. Despite a plethora of experimental studies on phyllotaxis, understanding of molecular mechanisms of pattern initiation in plants remains fragmentary. Live imaging of growth dynamics and physicochemical properties at the shoot apex of mutants displaying stable changes from one pattern to another should provide mechanistic insights into organ initiation patterns.
Editor's suggested further reading in BioEssays Computer simulation: The imaginary friend of auxin transport biology Abstract
Local auxin accumulation marks the organ initiation and controls the organ positioning in plants. The dynamics of auxin accumulation is mediated by the concentration and orientation of auxin transporters, which in turn are controlled by an intricate feedback mechanism involving both transport and mechanical strain.