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Turkish Journal of Botany

DOI

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Abstract

Studies were undertaken for induction of resistance against acute ozone exposure in Rhinacanthus nasutus (L.) Kurz. plants using ozone. Callus induced from Rhinacanthus nasutus leaf explants on Murashige & Skoog's (MS) medium supplemented with 3.40 µM of 2,4-dichlorophenoxy acetic acid (2,4-D) were treated with different concentrations of ozone (T_1 = 1.0 µmol mol^{-1} (±0.2), T_2 = 1.5 µmol mol^{-1} (±0.2), T_3 = 2.0 µmol mol^{-1} (±0.2)), and for the control (C) filtered air was supplied. Regeneration of shoots was obtained by culturing ozone-treated calli on MS medium supplemented with 5.57 µM of kinetin (KIN) and 1.30 µM of gibberellic acid (GA3). The frequency of regeneration of shoots from the callus was T_1 = 60%, T_2 = 49%, T_3 = 32%, but for the control 81% regeneration was obtained. Regenerated shoots were rooted in half-strength MS medium containing 4.92 µM of indole-3 butyric acid (IBA) and successfully acclimatised. The seedlings regenerated from ozone treated calli are referred to as T_1, T_2 and T_3 seedlings and the seedlings regenerated from filtered air-treated callus are referred to as control seedlings. T_1 seedlings hold remarkably more total soluble phenol content than T_2 and T_3 compared to the control seedlings. T_1 seedlings developed more resistance to withstand acute ozone exposure by increased phenylalanine ammonia-lyase activity and possessed more chlorophyll pigments and decreased H_2O_2 content relative to T_2 and T_3 seedlings compared to control seedlings.

First Page

135

Last Page

141

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