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

IANNONE MF; ROSALES EP; GROPPA MD; BENAVIDES MP

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-type SR1 and transgenic CAT1AS plants (with a basal reduced CAT activity) was evaluated after exposure to the herbicide paraquat (PQ). Superoxide anion (O2.−) formation was inhibited at 3 or 21 h of exposure, but H2O2 production and ion leakage increased significantly, both in SR1 or CAT1AS leaf discs. NADPH oxidase activity was constitutively 57% lower in non-treated transgenic leaves than in SR1 leaves and was greatly reduced both at 3 or 21 h of PQ treatment. Superoxide dismutase (SOD) activity was significantly reduced by PQ after 21 h, showing a decrease from 70% to 55%, whereas catalase (CAT) activity decreased an average of 50% after 3 h of treatment, and of 90% after 21 h, in SR1 and CAT1AS, respectively. Concomitantly, total CAT protein content was shown to be reduced in nontreated 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 underlying PQ-induced cell death were possibly not related exclusively to ROS formation and oxidative stress in tobacco wild-type or transgenic plants.