Changes in cytokinin levels and metabolism in tobacco (Nicotiana tabacum L.) explants during in vitro shoot organogenesis induced by trans-zeatin and dihydrozeatin

Klemš M., Slámová Z., Motyka V., Malbeck J., Trávníčková A., Macháčková I., Holík J., Procházka S.

Keywords: beta-glucosidase, cytokinin oxidase/dehydrogenase, dihydrozeatin, organogenesis in vitro, trans-zeatin
Abstract: The uptake and metabolism of trans-zeatin (Z) and/or dihydrozeatin (DHZ), in correlation with cytokinin oxidase/dehydrogenase (CKX) and beta-glucosidase activity, were studied in leaf segments derived from wild-type (WT) and transgenic (T) tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) during in vitro induction of shoot organogenesis. T explants harbored the maize gene Zm-p60.1 beta-glucosidase. Higher levels of shoot regeneration were observed on T explants in the early stages of cultivation. In WT explants, the content of cytokinin (CK)-O- and N-glucosides increased. In T explants, a higher content of Z-9-riboside (ZR) and Z-9-riboside-5´-monophosphate (ZRMP) and higher CKX activity during the early stage of cultures were found. A positive correlation was obtained for bioactive CK content and the organogenic response in T explants. Our results indicate a connection between the organogenic capacity of tobacco explants, metabolism of endogenous CKs and uptake of exogenous CKs from the cultivation medium.
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IEB authors: Josef Holík, Jiří Malbeck, Václav Motyka, Alena Trávníčková