Comparison of stimulatory effect of cytokinins adenine and urea derivatives on the level of some components in Wolffia arrhiza (L.) Wimm. (Lemnaceae)

The effect of cytokinins with different chemical structures, adenine-type: N6-benzylaminopurine (BAP), N6-furfurylaminopurine (FAP) and derivative of urea - 1,3-diphenylurea (DPU) applied in optimal physiological concentrations of 10-6-10-4 M on the mixotrophic plant Wolffia arrhiza during the period of 20 days of culture, was examined. The cytokinin highest influence on the metabolites level in W. arrhiza fresh weight was demonstrated in the range of concentrations 10-6-10-5 M between the 5th and the 10th day of culture. Among used cytokinins, the highest stimulative effect on the content of water-soluble proteins can be attributed to DPU (181%), slightly lower to BAP (167%) and the lowest to FAP (113%) in comparison with the control culture (100%). BAP was found to exert the most stimulative activity on nucleic acids accumulation (DNA+RNA) to the maximum value (127%). FAP and DPU possessed weaker stimulative activity increasing the nucleic acid content to the level of 120% and 118%, properly. The content of monosaccharides was stimulated to the highest level of 174% in FAP treated plants, to 151% in case of BAP and in case of DPU to 144%. Whereas, the highest increase of the photosynthetic pigments content (chlorophyll a and b as well as total carotenoids) to the range of 123-146% in W. arrhiza culture in the presence of DPU, was observed. Under the influence of FAP the accumulation of photosynthetic pigments was stimulated less effectively to the range of 113-140%. When the plants grew with BAP the chlorophylls and carotenoids contents increased to the lowest values of 119-131%. On the other hand, the content of total carotenoids was stimulated only during the first days of culture, then between the 15th and the 20th day it was inhibited by all applied adenine and urea-type cytokinins to the value of 70%. The results indicate that there is no quantitative correlation between the structure of all analysed cytokinins and their influence on the biochemical responses of W. arrhiza.