UV-B-INDUCED AND OXIDATIVE STRESS-INDUCED INCREASE IN NICOTINAMIDE AND TRIGONELLINE AND INHIBITION OF DEFENSIVE METABOLISM INDUCTION BY POLY(ADP-RIBOSE)POLYMERASE INHIBITOR IN PLANT-TISSUE

Nicotinamide and trigonelline contents increased in Catharanthus roseu s tissue culture after exposure to 2,2'-azobis(2-amidinopropane)dihydr ochloride (AAPH) or vanadylsulfate and in Pisum sativum leaves after e xposure to UV-B radiation, Vanadylsulfate increased phenylalanine ammo nialyase (PAL) activity and the content of reduced and oxidized glutat hione in C. roseus tissue culture. The increases in PAL activity cause d by 2 mM AAPH or 0.2 mM vanadylsulfate were prevented by 0.1 mM 3-ami nobenzamide (3-AB), an inhibitor of poly(ADP-ribose)polymerase. Presen t results support the hypothesis [Berglund T., FEBS Lett. (1994) 351, 145-149] that nicotinamide and/or its metabolites may function as sign al transmitters in the response to oxidative stress in plants and that poly(ADP-ribose)polymerase has a function in the induction of defensi ve metabolism.