The biological activity of cytokinin derivatives in the soybean callus bioassay

Abstract

The effect of 28 natural and synthetic cytokinins, including cytokinin nucleotides, the growth of soybean cotyledonary callus was investigated . Generally the nucleosides and nucleotides gave a slightly better response than their respective free bases. The differences in response were, however, not significant and there is a distinct possibility that rapid interconversions between these three types of cytokinin occur within the tissue . The 0-glucosides of Z and ZR were the most active . Glucosylation in the 3, 7 and 9 positions reduced activity . In the case of BA-derivatives the order of activity of the N-glucosides was 3G > 9G > 7G . Since iso-pentenyl derivatives had little activity they may be very difficult to detect using the soybean callus bioassay .Abbreviations . Z = zeatin ; DHZ = dihydrozeatin; IP = iso-pentenyladenine ; BA = benzyladenine ; K = Kinetin; R = riboside ; MP = monophosphate; OG = 0-glucoside ; 3G = 3-glucoside ; 7G = 7-glucoside; 9G = 9-glucoside ; GC-MS = gas chromatography -mass spectrometry .

Euglena gracilis(Euglenophyceae) produces abscisic acid and cytokinins and responds to their exogenous application singly and in combination with other growth regulators

“…Stirk et al (2003Stirk et al ( , 2009 observed only low levels of O-glucosides in microalgae and seaweeds. O-glucosides are considered to be the hormone storage forms, thought to function in higher plants as a slow-release reserve refilling the active aglycons, thereby ensuring a continuous supply of free CKs over a prolonged period of time (Van Staden & Drewes, 1991;Strnad, 1997). Ordog et al (2004) and Stirk et al (2003) suggested that because O-glucosides are resistant to degradation by CK oxidase, they may function to ensure the presence of free active CKs in microalgae where CK oxidase activity is high.…”

ENDOGENOUS CYTOKININS IN THREE GENERA OF MICROALGAE FROM THE CHLOROPHYTA1

“…This suggests that cis isomers may play a more active role in regulating cytokinin levels in plants than previously thought (Martin et al 2001). Alternatively, the cis isomer may be a means of detoxification because it has lower levels of biological activity than the trans isomer (van Staden and Drewes 1991). This may also explain why in the microalgae there are no N‐glucosides which are considered to be biologically inactive deactivation products (Letham and Palni 1983).…”

Optimizing the micropropagation protocol for the endangered Aloe polyphylla: can meta-topolin and its derivatives serve as replacement for benzyladenine and zeatin?

“…BA, kinetin and zeatin were purchased from SIGMA. The soybean callus bioassay developed by Miller (1965), as used by Van Staden and Drewes (1991), was employed to determine the biological activity of the different cytokinins. Four 25 ml Erlenmeyer flasks each containing 15 ml of media solidified with 1% agar (Oxoid No.…”