|
|
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.
|
|
| |
|
| |
|
|
Enhanced plant tolerance after ABA application
Pospíšilová, Jana ; Synková, Helena ; Baťková, Petra ; Haisel, Daniel ; Pešek, Bedřich
Critical period during micropropagation is often ex vitro transfer. The aim of this research was to determine whether exogenous abscisic acid (ABA) applied immediately after ex vitro transfer of in vitro grown tobacco regenerants can not only decrease transpiration rate and so partially eliminate their wilting but also ameliorate photoinhibition and oxidative stress. After ABA application, ABA content in tobacco leaves increased considerably, stomatal conductance and transpiration rate decreased more than in control plants and their wilting was limited. Chlorophyll and -carotene contents were higher in these plants, but the content of xanthophyll cycle pigments was not increased. However, the degree of xanthophyll cycle pigments deepoxidation was decreased what also suggested less stress in these plants. Applied ABA stimulated activities of some antioxidative enzymes but not immediately after ex vitro transfer.
|
|
| |
|
| |
guest ::
