Regulation of the flowering time of <i>Arabidopsis thaliana</i> by thylakoid ascorbate peroxidase

Abstract

Flowering time of higher plants is precisely controlled by various exogenous and endogenous factors. Recent researches implied that H₂O₂ is a potential flowering initiation factor. In order to confirm this hypothesis, thylakoid ascorbate peroxidase (tAPX) overexpressing Arabidopsis, the mutant line containing a T-DNA insertion and the wild type have been analyzed in this study, since APX was an important enzyme scavenging H₂O₂ in plant cells. It was found that during the vegetative growth stage there was no phenotypic difference among the three lines under common conditions, but 3,3’-diaminobenzidinetetrahydrochloride (DAB) staining showed that the endogenous H₂O₂ content varied: the mutant line had the highest content; the wild type took the second place, while the tAPX-overexpressing line had the lowest H₂O₂ content. This trend was in accordance with the bolting and flowering time during the following reproductive growth stage: the mutant bolted and flowered first, followed by the wild type, and the overexpressing line bolted and flowered last. This correlation confirmed the previous hypothesis that “H₂O₂ is a possible factor in flowering induction”.

Keywords: Ascorbate peroxidase, Arabidopsis thaliana, flowering time, hydrogen peroxide.