|
Changes in cytokinin contents and metabolism in spinach in response to zinc excess in soil
Žižková, E. ; Gajdošová, Silvia ; Pavlíková, D. ; Pavlík, Milan ; Száková, J. ; Motyka, Václav
Changes in endogenous cytokinin (CK) contents and metabolism in spinach (Spinacia oleracea L.) responding to excessive amounts of zinc in soil were studied. Application of three zinc rates in soil (250, 500, 750 mg.kg-1) resulted in a progressive (1.7- to 3.3-times) increase of endogenous CKs in spinach leaves. This increase was predominantly due to accumulation of inactive and storage CK forms (N- and O-glucosides) and was accompanied with an enhanced activity of cytokinin oxidase/dehydrogenase (CKX), the key CK degradative enzyme, especially on the highest zinc rate (750 mg.kg-1 soil). On this rate, maximum endogenous CK concentrations in both control and stressed plants were found at the first and the last samplings, i.e. in the course of very young leaf development and just before or during flowering. The CKX activity of stressed plants exceeded that of controls during the whole development and reached the maxima at the last sampling of treated plants.
|
guest ::
