Regulation of the flowering time of Arabidopsis thaliana 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.