PSII photochemistry, oxidative damage and anti-oxidative enzymes in arsenate-stressed Oryza sativa L. seedlings

The aim of the present study was to quantify the arsenic-induced damage in rice seedlings in terms of certain physiological and biochemical parameters. For this, hydroponically grown Oryza sativa L. seedlings were exposed to certain doses of As-V as Na2HAsO4 (10, 25, 50 and 100 mu M). All the tested doses manifested in a significant loss in the pigments content and photosynthesis, which culminated in retarded growth of the seedlings. The As-V-mediated decline in PSII photochemistry could be correlated with the decline in phi P-0, (0), phi E-0 and PIABS. In vitro and in vivo detection of and H2O2 and the consequent rise in malondialdehyde equivalents after As-V treatments stimulated the anti-oxidant enzymes, that is, superoxide dismutase (SOD) (except at 50 and 100 mu M As-V), peroxidase and catalase, activity which was further confirmed by the native polyacrylamide gel electrophoresis (PAGE) that also revealed the least expression of SOD isoforms against 50 and 100 mu M As-V treatment. The present investigation is a categorical demonstration of the inhibitory behaviour of As-V in O. sativa L. seedlings. At lower doses of arsenate, reactive oxygen species and anti-oxidants cooperatively acted in such a way that the impacts of the stress were far lesser on various growth and physiological parameters.