Characterization of NADPH-dependent oxidoreductase induced by auxin in rice.
An NADPH-dependent oxidoreductase (NADPH-DO) with an isoelectric point of 5.2 and a molecular mass of 35 kDa was isolated from suspension-cultured rice cells. NADPH-DO was inducible by auxin and gibberellin. NADPH-DO mRNA was expressed in roots and leaf sheaths of rice seedlings, but not in leaf blades. The levels of NADPH-DO mRNA and protein in suspension-cultured cells were increased by auxin; they were further raised by the application of zinc. In contrast, NADPH-DO mRNA and protein accumulation in intact roots was stimulated by auxin, but in this case the stimulation was inhibited by zinc. Auxin-induced callus growth and root formation in intact rice plants were further enhanced by zinc. These results indicate that high levels of NADPH-DO are necessary for auxin- and zinc-induced callus formation, and imply that zinc plays a role in the regulation of NADPH-DO induction by auxin.
Oguchi
Keiko
K
Faculty of Agriculture, Miyazaki University, Miyazaki, 889-2192 Japan.
Tanaka
Naoki
N
Komatsu
Setsuko
S
Akao
Shoichiro
S