Okadaic acid did not change the nitrate reductase activation state in tomato seedlings

In this study, the total and actual nitrate reductase (NR) activity, and NR activation state, in tomato seedlings ( Solanum lycopersicum cvs. Kmicic and Faworyt) treated with okadaic acid (OA) was evaluated. Seedlings were grown in a half-strength Murashige and Skoog (MS) medium in a growth chamber at day/night temperatures of 22/20 °C, a photon flux density of 150 µmol m -2 s -1 , and a 16-h photoperiod. After 10 days, plants were transferred into MS medium with 0 (control), 0.01, 0.05, 0.1, 0.5, 1.0 µM OA. It was found that the total and actual NR activity increased in Kmicic leaves treated with 0.1, 0.5, and 1.0 µM OA compared to control. However, the NR activation state did not change in both roots and leaves of OA-treated tomato seedlings.