Abstract
Plants generate active oxygen species (AOS) by environmental stress such as salinity. The generated AOS involves increased activity of antioxidant enzymes. However, catalase activity was often decreased by stress. Previous studies reported that catalase binds to salicylic acid (SA), and its activity is inhibited. We studied that relation between SA and catalase, and induction or inhibition of benzoic acid 2-hydroxylase (BA2H, cytochromeP-450) which catalyzes SA biosynthesis, in salt stress.
In rice treated by NaCl, catalase activity decreased and SA content increased. We suggested that SA accumulated by salt stress was decreased catalase activity. NaCl treatment increased BA2H activity. It was, therefore, considered that the activation of BA2H by salt stress increased SA content. We investigated the inhibition of BA2H by various compounds (gibberellin biosynthesis inhibitors, herbicides and substrate analogues). Gibberellin biosynthesis inhibitors were the most effective. It is suggested that direct P-450 inhibitor is also effective inhibitor of BA2H.
