Relationships between the morphological features of phyllotaxis and its patterning mechanism

Abstract

Phyllotaxis of plants shows regular and beautiful patterns with a limited variety, which mostly fall within several types. Phyllotactic patterns have long been studied and described by morphological analysis. Now phyllotactic patterns are considered to be spontaneously generated through positional relationships between leaf primordia resulting from inhibition of new primordium formation by existing primordia at their vicinity, which has been supported by successful production of major phyllotactic patterns in computer simulations with mathematical models assuming such inhibitory effect. Recent molecular studies have identified the inhibitory effect as the competition for auxin at the molecular level, leading to the establishment of the framework of the mechanism of phyllotactic pattern formation. This framework is expected to enable search for determinants of a particular phyllotactic pattern from its morphological features. The aim of this article is to propose such new approach. Here we review morphological features of phyllotactic patterns and their measurement, introduce mathematical models of phyllotactic pattern formation, and discuss how to estimate the parameter values of the mathematical model from the morphological features of phyllotactic patterns.