The effect of natural and synthetic auxins on the growth, metabolite content and antioxidant response of green alga Chlorella vulgaris (Trebouxiophyceae)

Abstract

The effect of exogenously applied natural [indole-3-acetic acid (IAA), phenylacetic acid (PAA), indole-3-butyric acid (IBA)] and synthetic [1-naphthaleneacetic acid (NAA)] auxins on the growth and metabolism of green microalga Chlorella vulgaris was examined. Exogenous auxins acted in a concentration-dependent manner on algal growth. Phytohormones at concentration of 100 lM inhibited algal growth expressed as the number of cells. IAA and IBA displayed the highest biological activity at 0.1 lM, whereas PAA and NAA were characterized by the greatest stimulatory effect on the number of cells at 1 lM. Treatment with IAA and IBA at 0.1 lM or NAA and PAA at 1 lM increased the concentration of photosynthetic pigments, monosaccharides and soluble proteins in C. vulgaris. Moreover, all auxins stimulated enzymatic (ascorbate peroxidase, catalase, superoxide dismutase) and non-enzymatic antioxidant (ascorbate, glutathione) systems in C. vulgaris, and therefore, suppressed lipid peroxidation and hydrogen peroxide accumulation. The data supports the hypothesis that auxins play a central role in the regulation of C. vulgaris growth and metabolism and the components of cellular redox systems that are thought to have a prominent role in the regulation of auxindependent processes.

Stimulatory effect of indole-3-acetic acid and continuous illumination on the growth of Parachlorella kessleri

“…The growth rate of Scenedesmus quadricauda in the presence of IAA added in the range of 5.0 -60 mg l -1 was lower and its maximum value was 0.64 x 10 -2 day -1 ; in turn, it was 0.65 10 -2 day -1 for the IAA non-supplemented culture (Liu et al, 2016). Piotrowska-Niczyporuk and Bajguz (2014) indicate that the growth of Chlorella vulgaris was stimulated at 0.1 µM of IAA (under 50 µmol photon m -2 s -1 light intensity and 16/8 h light/dark cycle); however, inhibitory effects were noted at a concentration of 100 µM of IAA. Studies of exogenously added IAA (100 µM) under continuous illumination (80 µmol m -2 s -1 ) showed no effect on the cell growth of C. vulgaris (Jusoh et al, 2015).…”

“…Exogenous auxin increases the growth rate of algae such as Chlorella vulgaris, Chlorella sorokiniana, Chlamydomonas reinhardtii, Haematococcus pluvialis, Pleurochrysis carterae, and Phaeodactylum tricornutum (Lu and Xu, 2015;Park et al, 2014;Piotrowska-Niczyporuk and Bajguz, 2014).…”

Phytohormones and Effects on Growth and Metabolites of Microalgae: A Review

“…Similar evidence was found in C. vulgaris [23], in which IAA exhibited the highest accumulation of lipids with enriched palmitic (C16:0) and stearic (C18:0) acids. Auxins can also enhance, in addition to growth and lipids, the biosynthesis of pigments, monosaccharides, and soluble proteins in C. vulgaris [20]. Increases of 213-273% for chlorophyll a and b content and of 164-258% for carotenoid content of C. pyrenoidosa were also found with seven precursors and analogs of auxins supplemented [24].…”

“…In addition, 1-naphthaleneacetic acid (NAA) significantly increased the biomass yield of Chlorella pyrenoidosa by 2.2-fold [18]. It is hypothesized that auxins may promote growth by stimulating the activity of photosynthesis by boosting the contents of chlorophylls [19] and by activating cellular redox systems [20].…”

The Influence of Pterocladia capillacea Extract on Growth and Antioxidant System of Cicer arietinum

“…Seaweeds protect themselves against free radicals by developing antioxidant defense system, including enzymatic and non-enzymatic (Halliwell and Gutteridge, 2001;Burtin, 2003;Ashraf and Foolad, 2007;Piotrowska-Niczyporuk and Bajguz, 2013). The chickpea, Cicer arietinum L. (Family: Fabaceae), is one of the most important legume crop in the world because it has high nutritional value due to high protein content and dietary fiber.…”