N9-substituted aromatic cytokinins with negligible side effects on root development are an emerging tool for in vitro culturing

Abstract

Natural cytokinins as well as the majority of their synthetic derivatives show negative effects on root growth and development. Changes in morphology, primarily linked to the inhibition of the cell division in the meristematic zone, are manifested as thickening and shortening of the primary root and impaired lateral root branching. Rational design of cytokinin derivatives can partially overcome these drawbacks and reduce the negative effects. Using our database of cytokinin derivatives, we selected several aromatic cytokinin analogs with modifications at the N9 atom of the adenine moiety. We found that tetrahydropyranyl and tetrahydrofuranyl substitutions at the N9 atom led to enhanced acropetal transport of the modified cytokinin, and both derivatives also showed weak anticytokinin activity. Consequently, changes in the distribution of the active cytokinin pool together with gradual metabolic conversion of the modified cytokinin to its free form prevent root growth inhibition that limits cytokinin utilization in micropropagation techniques.

Keywords: :

• cytokinin
• N9-substituted cytokinins
• biotechnology
• root
• inhibition
• micropropagation
• tissue culture

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

We would like to thank Martin Tkáč and Aneta Wanderlová for their technical assistance. This work was supported by grants GAP522/10/1141 and GAP501/10/1450 from the Czech Science Foundation and COST project LD12061.