Abstract

Cytokinins are deactivated in radish cotyledons by conversion to 7- and 9-glucosides. In a search for inhibitors of this metabolism, the following compounds were found to be effective: (a) 6-benzylamino-2-(2-hydroxyethylamino)-9-methylpurine; (b) 3-isobutyl-1-methylxanthine; (c) papaverine; (d) theophylline; (e) caffeine; and (f) theobromine. The order of effectiveness was: (a)>(b)=(c)>(d)=(e)=(f). While the methylxanthines (b) and (d) inhibited formation of both 7- and 9-glucosides of 6-benzylaminopurine (BAP) approximately equally, compounds (a) and (c) preferentially inhibited formation of BAP 9-glucoside. Inhibition of BAP glucoside formation by (a) at 1.3 mM elevated the level of free BAP and BAP nucleotide 23- and 94-fold, respectively. While abscisic acid (ABA) suppressed conversion of zeatin riboside to zeatin 7-glucoside in radish cotyledons, it did not inhibit conversion of BAP to glucosides. Hence, ABA probably does not inhibit the glucosylating enzymes directly but rather reduces the availability of free zeatin when zeatin riboside is supplied. Auxins and nutrient supply did not affect conversion of zeatin riboside to zeatin 7-glucoside. Relative to cotyledons developed in light, those developed in darkness had a reduced capacity to convert zeatin riboside to zeatin 7-glucoside. The results presented have identified types of chemical structures which could be developed to provide more effective inhbitors of cytokininN-glucosylation.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.