Verbena officinalis Verbenaceae (Lamiales): a new plant model system for phyllotaxis research

Abstract

Phyllotactic diversity and developmental transitions between phyllotactic patterns are not fully understood. The plants studied so far, such as Magnolia, Torreya or Abies, are not suitable for experimental work, and the most popular model plant, Arabidopsis thaliana, does not show sufficient phyllotactic variability. It has been found that in common verbena (Verbena officinalis L.), a perennial, cosmopolitan plant, phyllotaxis differs not only between growth phases in primary transitions but also along the indeterminate inflorescence axis in a series of multiple secondary transitions. The latter are no longer associated with the change in lateral organ identity, and the sequence of phyllotactic patterns is puzzling from a theoretical point of view. Data from the experiments in silico, confronted with empirical observations, suggest that secondary transitions might be triggered by the cumulative effect of fluctuations in the continuously decreasing bract primordia size. The most important finding is that the changes in the primary vascular system, associated with phyllotactic transitions, precede those taking place at the apical meristem. This raises the question of the role of the vascular system in determining primordia initiation sites, and possibly challenges the autonomy of the apex. The results of this study highlight the complex relationships between various systems that have to coordinate their growth and differentiation in the developing plant shoot. Common verbena emerges from this research as a plant that may become a new model suitable for further studies on the causes of phyllotactic transitions.

A new mathematical model of phyllotaxis to solve the genuine puzzle spiromonostichy

“…The mean divergence angle of costoid phyllotaxis of this plant in the adult vegetative phase was about 54°. Comparable small divergence angles are found in only few plants outside Costaceae (Rutishauser, 1998; Zagórska-Marek et al, 2021). Picea abies is one of such exceptional plants and was reported to have a divergence angle of 56.4° (Rutishauser, 1998).…”

Beyond Fibonacci patterns and the golden angle: phyllotactic variations and their cellular origin

“…In particular we highlight patterns "outside" Fibonacci patterns and the evolutionary origins of phyllotaxis. Three review articles discussing general aspects (Yin 2021), stochasticities (Kitazawa 2021), and symmetries (Yonekura and Sugiyama 2021); and three original research articles focusing on pattern regeneration (Zhang et al 2021b), a new system for studying phyllotactic transitions (Zagórska-Marek et al 2021), and the origin of phyllotaxis (Kamamoto et al 2021), are included in this special issue.…”

“…Therefore, to study the diversity of phyllotaxis beyond Fibonacci patterns, a new model system is required. Zagórska-Marek et al (2021) showed that common verbena (Verbena officinalis L.) has preferable features in this regard. This perennial plant is suitable for laboratory experiments, and has phyllotactic transitions not only between growth phases but also within the indeterminate inflorescence axis, without changing the identity of lateral organs.…”