Document Type : Research Paper
Authors
Abstract
Thymus daenensis Celak. is an endemic plant species in Iran used for medicinal purposes. It seems that In vitro culture is a useful technique for its propagation. In vitro culture conditions cause water stress or hyperhydricity in tissues due to the cut in the plant tissue and changes in levels of plant hormones compared to natural conditions and may vary depending on the type of medium, type of agar and available water. Hyperhydricity syndrome is one of the major problems that occur in in vitro growth and through a deformity prevents the propagation of plants. In shoot culture of Thymus daenensis Celak., hyperhydricity happens commonly. In this investigation, the effect of benzyladenine and salicylic acid were studied on shoot hyperhydricity syndrome. For this purpose, disinfected seeds were cultured into glass jars containing Murashige and Skoog (MS) medium with benzyladenine (0.1mgl-1). Non benzyladenine-treated plantlets were transferred to the same medium and benzyladenine-treated plantlets were cultured in four experimental media including without benzyladenine, with 1mgl-1 benzyladenine in presence or without 5µM salicylic acid. Afterward, effects of the mentioned treatments on hyperhydricity, morphological and physiological characteristics of the plant were measured. Results showed that benzyladenine singly caused hyperhydricity in shoot explants of Thymus daenensis. After transferring the explants to the medium free of benzyladenine, hyperhydricity reversed toward normal state and the presence of salicylic acid improved this reversion. Salicylic acid reduced water content in shoot explants and enhanced the amount of photosynthetic pigments. In benzyladenine treated sample, the hyperhydricity was not reversed by salicylic acid.
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