OsGLO4 is involved in the formation of iron plaques on surface of rice roots grown under alternative wetting and drying condition

Background and aim The molecular physiological mechanism of alternative wetting and drying (AWD) promoting iron plaque (IP) formation is unknown. Here, we report that a glycolate oxidase (GLO) gene, OsGLO4 contributes to AWD-induced IP formation. Methods Rice plants were grown in sand to explore the relationship among IP content, GLO activity, H2O2 concentration and OsGLO4 expression under AWD treatment. Results AWD significantly promoted GLO activity, OsGLO4 expression,and IP content in rice roots. Overexpressing OsGLO4 (OX) showed more 46.2% IP content than wild type (WT). Results with X-ray diffraction analysis indicated that OX also had a higher proportion of FeIII compound in IP in comparison to WT. The activity of GLO and H2O2 concentration in OX roots were 170.3% and 126.7% higher than those of WT. Interestingly, H2O2 distribution in epidermal cells was consistent with the spatial distribution of IP. Treatment with glycolic acid raised GLO activity by 88.9% and IP content by 33.3%; while α-hydroxy-2-pyridinemethanesulfonic acid inhibited GLO activity and reduced IP content. Exogenous H2O2 or treatment with aminotriazole increased the quantities of IP significantly, while dimethylthiourea reduced it. Conclusion OsGLO4 is involved in the formation of IP by mediating GLO activity and H2O2 production under AWD condition.