Reactive oxygen species formation and cell death in catalase-deficient tobacco leaf discs exposed to paraquat

IANNONE M.F.; ROSALES E.P.; GROPPA M.D.; BENAVIDES M.P.

BIOLOGICAL TRACE ELEMENT RESEARCH

HUMANA PRESS INC

Lugar: Oregon; Año: 2012 vol. 146 p. 246 - 255

0163-4984

In the present work, the response of tobacco (Nicotiana tabaccum L.) wild-ty pe SR1 and transgenic CAT1AS plants (with a basal reduced CAT activ ity ) was ev aluated af ter exposure to the herbicide paraquat (PQ). Superoxide anion (O2 −) f ormation was inhibited at 3 or 21 h of exposure, but H2O2 production and ion leakage increased signif icantly , both in SR1 or CAT1AS leaf discs. NADPH oxidase activ ity was constitutiv ely 57% lower in non-treated transgenic leav es than in SR1 leav es and was greatly reduced both at 3 or 21 h of PQ treatment. Superoxide dismutase (SOD) activ ity was signif icantly reduced by PQ af ter 21 h, showing a decrease f rom 70% to 55%, whereas catalase (CAT) activ ity decreased an av erage of 50% af ter 3 h of treatment, and of 90% af ter 21 h, in SR1 and CAT1AS, respectiv ely . Concomitantly , total CAT protein content was shown to be reduced in non-treated CAT1AS plants compared to control SR1 leaf discs at both exposure times. PQ decreased CAT expression in SR1 or CAT1AS plants at 3 and 21 h of treatment. The mechanisms underly ing PQ-induced cell death were possibly not related exclusiv ely to ROS f ormation and oxidativ e stress in tobacco wild-ty pe or transgenic plants.