Allantoin accumulation mediated by allantoinase down-regulation and transport by Ureide Permease 5 (UPS5) confers salt stress tolerance to Arabidopsis plants

Abstract

In several reports, variations in the content of purine degradation metabolites has been associated with plant responses to different stress conditions and leaf senescence, but the subjacent molecular mechanisms remained poorly understood. A recent study demonstrated that the ureide allantoin (ALN), a product of the purine degradation pathway, induces de novo biosynthesis and deconjugation of the stress hormone abscisic acid (ABA). This was related to a better tolerance to osmotic and water stress. Other studies suggest a protective effect of ALN and allantoate against ROS, but the mechanisms implied remain unknown. The ureides ALN and allantoate are products of the purine degradation pathway (Fig. 1). ALN is hydrolyzed to allantoate through allantoinase (AtALN).