Circadian life without micronutrients: effects of altered micronutrient supply on clock function in Arabidopsis

The plant circadian clock is formed by a number of interlocked feedback loops that control the expression of thousands of genes. Genetic and pharmacological approaches towards the study of the plant clock are routinely carried out on Murashige and Skoog growth medium, which is both Fe-replete and Cu-deficient. However, it has recently become clear that the plant clock responds to available iron (Fe) supply: circadian pace slows down under conditions of Fe deficiency; circadian period progressively shortens with increasing Fe supply. Here, we describe several growth media that may be used to study the effects of varying micronutrient supply on the circadian clock, in which deficiency in a given micronutrient are imposed by the addition of a specific chelator or, alternatively, by using EDTA-washed agar as gelling agent, thus minimizing micronutrient contamination.