title: Synergistic effect of auxins and brassinosteroids on the growth and regulation of metabolite content in the green alga Chlorella vulgaris (Trebouxiophyceae).
abstract: The relationships between brassinosteroids (BRs) (brassinolide, BL; 24-epiBL; 28-homoBL; castasterone, CS; 24-epiCS; 28-homoCS) and auxins (indole-3-acetic acid, IAA; indole-3-butyric acid, IBA; indole-3-propionic acid, IPA) in the regulation of cell number, phytohormone level and metabolism in green alga Chlorella vulgaris were investigated. Exogenously applied auxins had the highest biological activity in algal cells at 50 μM. Among the auxins, IAA was characterized by the highest activity, while IBA - by the lowest. BRs at 0.01 μM were characterized by the highest biological activity in relation to auxin-treated and untreated cultures of C. vulgaris. The application of 50 μM IAA stimulated the level of all detected endogenous BRs in C. vulgaris cells. The stimulatory effect of BRs in green algae was arranged in the following order: BL > 24-epiBL > 28-homoBL > CS > 24-epiCS > 28-homoCS. Auxins cooperated synergistically with BRs stimulating algal cell proliferation and endogenous accumulation of proteins, chlorophylls and monosaccharides in C. vulgaris. The highest stimulation of algal growth and the contents of analyzed biochemical parameters were observed for the mixture of BL with IAA, whereas the lowest in the culture treated with both 28-homoCS and IBA. However, regardless of the applied mixture of BRs with auxins, the considerable increase in cell number and the metabolite accumulation was found above the level obtained in cultures treated with any single phytohormone. Obtained results confirm that both groups of plant hormones cooperate synergistically in the control of growth and metabolism of unicellular green alga C. vulgaris.
authors.affiliation: University of Bialystok, Institute of Biology, Department of Plant Biochemistry and Toxicology, Swierkowa 20 B, 15-950 Bialystok, Poland. Electronic address: abajguz@uwb.edu.pl.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Bajguz
authors.forename: Alicja
authors.initials: A
authors.lastname: Piotrowska-Niczyporuk
mesh_terms: D060406:Brassinosteroids / Q000494:pharmacology*; D048408:Chlorella vulgaris / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D004357:Drug Synergism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D013260:Steroids, Heterocyclic / Q000494:pharmacology*
chemical_list: D060406:Brassinosteroids; D007210:Indoleacetic Acids; D013260:Steroids, Heterocyclic; C023623:brassinolide
keywords: 24-epiBL; 24-epiCS; 24-epibrassinolide; 24-epicastasterone; 28-homoBL; 28-homoCS; 28-homobrassinolide; 28-homocastasterone; 4-Cl-IAA; 4-chloroindole-3-acetic acid; 6-deoxo-TY; 6-deoxoTE; 6-deoxoteasterone; 6-deoxotyphasterol; AX; Auxins; BL; BR; Brassinosteroids; CS; Chlorophylls; Growth; IAA; IBA; IPA; Monosaccharides; Proteins; TE; TY; auxin; brassinolide; brassinosteroid; castasterone; indole-3-acetic acid; indole-3-butyric acid; indole-3-propionic acid; teasterone; typhasterol