UV-B- 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 roseus tissue culture after exposure to 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) or vanadylsulfate and in Pisum sativum leaves after exposure to UV-B radiation. Vanadylsulfate increased phenylalanine ammonia-lyase (PAL) activity and the content of reduced and oxidized gluthathione in C. roseus tissue culture. The increases in PAL activity caused by 2 mM AAPH or 0.2mM vanadylsulfate were prevented by 0.1 mM 3-aminobenzamide (3-AB), an inhibitor of poly(ADP-ribose)polymerase. Present results support the hypothesis [Berglund, T., FEBS Lett. (1994) 351, 145-149] that nicotinamide and/or its metabolites may function as signal transmittors in the response to oxidative stress in plants and that poly(ADP-ribose)polymerase has a function in the induction of defensive metabolism.