Exogenous H2O2 increased catalase and peroxidase activities and proline content in Nitraria tangutorum callus

Abstract

Antioxidative responses and proline accumulation induced by exogenous H2O2 were investigated in the callus from halophyte Nitraria tangutorum Bobr. H2O2-treated callus exhibited higher H2O2 content than untreated callus. The activities of catalase (CAT) and peroxidase (POD) significantly increased in the callus treated with H2O2, while ascorbate peroxidase (APX) activity decreased. In addition, significantly enhanced proline content was observed in the callus treated by H2O2, which could be alleviated by H2O2 scavenger dimethylthiourea and calcium (Ca) chelator ethylene glycol bis-(β-aminoethyl ether)-N,N,N',N'-tetra-acetic acid (EGTA). Moreover, γ-glutamyl kinase (GK) activity increased in H2O2-treated callus, but proline dehydrogenase (PDH) activity decreased significantly, and the reduction was partly abolished by EGTA or Ca channel blocker verapamil. Assays using a scanning electron microscope showed significantly enhanced Ca content in H2O2-treated callus.

Keywords

• antioxidative enzymes
• calcium
• γ
• -glutamyl kinase
• proline dehydrogenase