4th Central European Forum for Microbiology, Keszthely 2013
Detection of cytokinine and gibberellin-like plant hormones in Scenedesmus obtusiusculus Chlorella minutissima and Botryococcus braunii cultures
Erika Greipel, Zsuzsanna Bencsik, József Kutasi
Albitech Ltd, 1045, Berlini út 47-49
Abstract
Foliar fertilization is a widespread procedure in agriculture for applying inorganic fertilizers or other substances on the foliar surface of plants in order to enhance crop yield. The efficiency of foliar fertilization can be 8-20% better than solid fertilizers. Suspension of microalgae cultures has been used for long as foliar fertilizer, and according to recent research, it utilizes the hormone-producing capacity of algae. Numerous scientific studies have been published about algal cultures or extracts containing different types of plant hormones and their effect on plant growth and stimulation of germination. In our work, the cytokinine and gibberellin-like plant hormon production of axenic cultures of Scenedesmus obtusiusculus BEA(Banco Espanol de Algas) D01_12, Chlorella minutissima K 2012(Albitech collection) and Botryococcus braunii UTEX 2629 green alga strains were investigated. Both of these types of plant hormones significantly affect cell division. The gibberellins – as diterpenoids – stimulate cell division and cell growth so they promote the developing of leaves and the progress of blossoming. Additionally, these hormones induce the de novo syntesis of hydrolitic enzymes during the germination of seeds. Cytokinines delay senescence of leaves and they have morphogenetical effects as well. Detection of the mentioned plant hormones was conducted via thin layer chromatography following organic solvent extraction and evaporation (Tien et. al., 1979). Kinetin was present in evapored extracts of C. minutissima, S. obtusiusculus and B. braunii cultures as well. These evapored extract samples were observed also by HPLC-PDA. (Gupta et. al., 2011, Stirk et. al. 2004). The amount of kinetin was approximately 0,8 – 1,0 µg/ml (400 ng/ml in the algae liquid culture) and other cytokinin compontents were detected next to the kinetin in case of S. obtusiusculus. In the extracts of C. minutissima and Botryococcus braunii were approximately 0,1 – 0,2 µg kinetin/ml (40-80 ng/ml in the algae liquid culture). The citokinin-like activity of liquid cultures was also measured by cucumber cotyledon growing test. Samples – obtained by evaporation of S. obtusiusculus, a C. minutissima és a B. braunii cultures on low temperature – showed effects on the weight of cucumber cotyledons after 3 days of incubation time. The gibberellin-like activity was proved also by measuring amylase production of barley endosperm (Jones and Varner, 1966). Presence of gibberellin-like substances was detected in C. minutissima cultures. These results can serve as a good basis for the development of algae-based foliar fertilizer products and for a better understanding of their mode of action.
