We invite you to a seminar by Daniel Nedvěd, Laboratory of Hormonal Regulations in Plants

Cytokinin degradation in xylem – when transport meets metabolism

Cytokinin dehydrogenase (CKX) catalyses the cleavage of cytokinins, a major group of plant hormones. We performed a large-scale analysis of CKX proteins, revealing strong correlation between the identity of a variable ligand-binding motif and the protein’s predicted sub-cellular localization. These results portray CKX diversity as a widely conserved feature, allowing fine-tuning of cytokinin homeostasis maintenance.

We further studied CKX specializations in a model plant common oat (Avena sativa), an economically important crop. Quantifying AsCKX transcripts in different tissues revealed strong expression of extracellular forms in roots, suggesting their possible export to the xylem and degradation of cytokinins during their root-to-shoot transport.

In our subsequent experiments, we detected CKX activity in oat xylem sap and demonstrated its dependence on the external availability of nitrate, a mineral source of nitrogen. Our findings suggest that CKX activity in the xylem is involved in cytokinin homeostasis modulation during long-distance transport and has a potential role in nitrate signalling.

The seminar will be held at the Institute of Experimental Botany, Czech Academy of Sciences, Rozvojová 263, Prague 6, in the Library room (building B1, 1st floor).