Coumarin Interferes with Polar Auxin Transport Altering Microtubule Cortical Array Organization in Arabidopsis thaliana (L.) Heynh. Root Apical Meristem.

Leonardo Bruno,Luz Cabeiras-Freijanes,Luigi Lucini,Antonella Muto,Maria Letizia Madeo,Marco Minervino,Begoña Miras-Moreno,Fabrizio Araniti,Adriano Sofo,Emanuela Talarico

doi:10.3390/ijms22147305

Abstract

Coumarin is a phytotoxic natural compound able to affect plant growth and development. Previous studies have demonstrated that this molecule at low concentrations (100 µM) can reduce primary root growth and stimulate lateral root formation, suggesting an auxin-like activity. In the present study, we evaluated coumarin’s effects (used at lateral root-stimulating concentrations) on the root apical meristem and polar auxin transport to identify its potential mode of action through a confocal microscopy approach. To achieve this goal, we used several Arabidopsis thaliana GFP transgenic lines (for polar auxin transport evaluation), immunolabeling techniques (for imaging cortical microtubules), and GC-MS analysis (for auxin quantification). The results highlighted that coumarin induced cyclin B accumulation, which altered the microtubule cortical array organization and, consequently, the root apical meristem architecture. Such alterations reduced the basipetal transport of auxin to the apical root apical meristem, inducing its accumulation in the maturation zone and stimulating lateral root formation.

Highlights

IntroductionPlants have evolved marked metabolic plasticity to increase their defense and competitive abilities
Because of sessile conditions, plants have evolved marked metabolic plasticity to increase their defense and competitive abilities
Coumarin-treated roots were characterized by a reduction in MCN (46% lower than that in control) (Figure 2a), accompanied by a decrease in MZL (44%) (Figure 2b) and an increase in MZW (1.2-fold higher than that in control)

Summary

Introduction

Plants have evolved marked metabolic plasticity to increase their defense and competitive abilities They have developed different biochemical pathways involved in the biosynthesis of a plethora of specialized metabolites to counteract the challenges arising during their growth and development [1]. The plant–plant interaction mediated by specialized metabolites is known as allelobiosis (positive interaction) and allelopathy (negative interaction), and the molecules at the basis of these interactions are known as allelochemicals This ecological phenomenon plays an essential role in plant adaptation and competitive ability in the ecosystem, allowing plants to positively or negatively affect neighbouring species’ growth and development [5]

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Conclusion