Overproduction of putrescine changes the response to an oxidative challenge in Arabidopsis thaliana.

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

Villa Carlos Paz, Córdoba, Argentina

Congreso; XLIV Reunión Anual. Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2008

Polyamines (PAs) have been involved in a wide range of physiological processes in plants, such as stress responses and are considered as potential free radical scavengers and antioxidants. Arabidopsis thaliana plants (AT) that accumulate high levels of Put (line 9.12) were challenged with paraquat (PQ), to study if the susceptibility to oxidative stress was altered in transgenic plants. Analysis were performed in leaves from 30d-old wt or 9.12 plants, incubated in a rotatory shaker for 2 or 21 h with 10 or 100 ìM PQ. We evaluated superoxide and H2O2 formation using NBT and DAB staining, lipid peroxidation, chlorophyll and electrolyte leakage. The 9.12 line showed an enhanced Put content (58 %) measured in 30-d old entire plants. Formation of O-2 was decreased, while the content of H2O2 was increased at 21 hours, in wt or 9.12 lines treated with 10 or 100 µM PQ. The lower PQ concentration increased 6 times the leakage of solutes at 21 h, without detectable differences between wt or 9.12 lines, doubled TBARS levels and decreased chlorophyll to half of the controls, being these parameters slightly more affected in the transgenic cultivar. PQ at 100 ìM severely altered the studied variables. These preliminary results may suggest that leaves of transgenic AT plants with high Put content should present slightly higher susceptibility to the oxidative damage induced by PQ.