A model for leaf initiation: determination of phyllotaxis by waves in the generative circle

Area of Science:

• Plant developmental biology
• Biophysics
• Mathematical modeling

Background:

• Leaf arrangement on plant shoots (phyllotaxis) follows distinct patterns like spirals and whorls.
• The precise mechanisms governing primordia initiation and positioning remain incompletely understood.

Purpose of the Study:

• To propose a novel biophysical model for leaf primordia positioning on the shoot apical meristem.
• To explain the formation of both spiral and whorl phyllotactic patterns.
• To relate model parameters to observable leaf arrangement characteristics.

Main Methods:

• Development of a biophysical model based on signal propagation (auxin waves) in the epidermis.
• Analysis of wave periodicity to infer auxin transport dynamics.
• Formulation of an algorithm to predict leaf positions based on wave speeds and generative circle radius.

Main Results:

• The model describes primordia initiation via linear auxin waves propagating azimuthally.
• Auxin concentration build-up at wave intersections drives primordia formation.
• Asymmetric auxin transport explains higher-order spirals; model parameters correlate with phyllotactic patterns.

Conclusions:

• The proposed wave model provides a unified biophysical explanation for diverse phyllotactic patterns.
• The model integrates concepts of auxin transport, wave dynamics, and meristem geometry.
• Further biological experiments are suggested to validate the mathematical and molecular hypotheses.