NATURAL VARIATION IN THE CYTOKININ METABOLIC NETWORK IN ARABIDOPSIS THALIANA

Cytokinins are key determinants of cellular plasticity and are crucial for several processes that together determine overall fitness under any given conditions. Like any other signal molecule, the action of cytokinins is determined by the amount of active hormone exposed to receptor molecules, and the strength and duration of the subsequent signalling. Active hormone levels are the result of the combinatorial regulation of their biosynthesis, reversible and irreversible metabolic interconversion, and terminal degradation. The existence of genetically determined variation in geographically distinct populations within the model species Arabidopsis thaliana is being increasingly documented. We are exploring the cytokinin status of young Arabidopsis seedlings from a collection of accessions that represent maximal genetic diversity within the species. We will present data regarding cytokinin levels and some examples of physiological analysis of the variation in response to exogenous cytokinin. Comprehensive mapping of the variation in cytokinin metabolism will allow us to establish a basis for understanding how relatively minor changes in hormone status are used by the plant to form and fine-tune adaptive processes.