Distribution of superoxide and hydrogen peroxide in Arabidopsis root and their influence on root development: Possible interaction with peroxidases

Abstract

• The respective distribution of superoxide (O2•-) and hydrogen peroxide (H2O2), two reactive oxygen species (ROS) involved in root growth and differentiation, was determined within the Arabidopsis root tip. We investigated the effect of changing the levels of these ROS on root development and the possible interactions with peroxidases. • H2O2 was detected by confocal laser-scanning microscopy using hydroxyphenyl fluorescein (HPF). Both O2•- accumulation and peroxidase distribution were assessed by light microscopy, using nitroblue tetrazolium (NBT) and o-dianisidine, respectively. Root length and root hair length and density were also quantified following ROS scavenging. • O2•- was predominantly located in the apoplast of cell elongation zone, whereas H2O2 accumulated in the differentiation zone and the cell wall of root hairs in formation. Treatments that decrease O2•- concentration reduced root elongation and root hair formation, while scavenging H2O2 promoted root elongation and suppressed root hair formation. • The results allow to precise the respective role of O2•- and H2O 2 in root growth and development. The consequences of their distinct accumulation sites within the root tip are discussed, especially in relation to peroxidases.