Stirk W.A., Bálint P., Tarkowská D., Novák O., Strnad M., Ördög V., van Staden J.
PLANT PHYSIOLOGY AND BIOCHEMISTRY 70: 348-353, 2013

Keywords: Brassinolide; Brassinosteroids; Castasterone; Endogenous hormones; Gibberellins; GA6 ; Microalgae
Abstract: Endogenous gibberellins and brassinosteroids were quantified in 24 axenic microalgae strains 19 from the Chlorophyceae, Trebouxiophyceae, Ulvophyceae and Charophyceae microalgae 20 strains after 4 days in culture. This is the first report of endogenous gibberellins being 21 successfully detected in microalgae. Between 18 and 20 gibberellins were quantified in all 22 strains with concentrations ranging from 342.7 pg mg-1 DW in Raphidocelis subcapitata MACC 317 to 4746.1 pg mg-1 DW in Scotiellopsis terrestris MACC 44. Slower growing 24 strains (Scotiellopsis terrestris MACC 44, Gyoerffyana humicola MACC 334, Nautococcus 25 mamillatus MACC 716 and Chlorococcum ellipsoideum MACC 712) exhibited the highest gibberellin contents while lowest levels of gibberellins were found in faster growing strains (Raphidocelis subcapitata MACC 317 and Coelastrum excentrica MACC 504). In all strains, the active gibberellin detected in the highest concentration was GA6, the predominant intermediates were GA15 and GA53 and the main biosynthetic end-products were GA13 and GA51. Gibberellin profiles were similar in all strains except for the presence/absence of GA12 and GA12ald. To date this is the second report of endogenous brassinosteroids in microalgae. Brassinosteroids were detected in all 24 strains with concentrations ranging from 117.3 pg mg-1 DW in Raphidocelis subcapitata MACC 317 to 977.8 pg mg-1 DW in Klebsormidium flaccidum MACC 692. Two brassinosteroids, brassinolide and castasterone were determined in all the strains. Generally, brassinolide occurred in higher concentrations than castasterone.
DOI: IEB authors: Miroslav Strnad, Danuše Tarkowská