. 2017 Apr 25;8:515. doi: 10.3389/fmicb.2017.00515

Table 2.

An overview of various phytohormones produced by algae and their potential implication in microbial biotechnology.

Phytohormones	Cyanobacteria/algae	Relevant findings in microalgae	Potential implication for microalgal biotechnology	References
Abscisic acid (ABA)	Anabaena variabili, Ascophyllum nodosum^, Chlamydomonas reinhardtii^, Chlorella minutissima^, Chondracanthus^ sp., Coscinodiscus granii^, Draparnaldia mutabilis^, Dunaliella^* sp., Gelidium^* sp., Gracilaria^* sp., Gracilariopsis^* sp., Hypnea^* sp., Nannochloropsis oceanic^, Nostoc muscorum, Porphyra^ sp., Trichormus variabilis, Synechococcus leopoliensis	Exogenous ABA decreases growth rate in Nannochloropsis oceanica^* and Coscinodiscus granii^* Exogenous ABA improves stress tolerance to dehydration in Haematococcus pluvialis^, higher salinity in Dunaliella* sp.,^* and Chlamydomonas reinhardtii^; nitrogen deprivation in Nannochloropsis oceanica^; osmotic stress in Chlamydomonas reinhardtii^*	Improvement in stress tolerance.	Boyer and Dougherty, 1988; Hirsch et al., 1989; Kentzer and Mazur, 1991; Zahradnıckova et al., 1991; Marsšálek et al., 1992; Tominaga et al., 1993; Kobayashi et al., 1997; Yoshida et al., 2003; Hartung, 2010; Yokoya et al., 2010; Lu et al., 2014; Stirk et al., 2014
Auxins	Anabaena sp., Chlorella minutissima^, Chlorella pyrenoidosa^, Chondracanthus^* sp., Chroococcidiopsis sp., Ectocarpus siliculosus^, Gelidium^ sp., Gracilaria^* sp., Gracilariopsis^* sp., Hypnea^* sp., Nostoc sp., Oscillatoria sp., Phormidium sp., Porphyra^* sp., Prionitis lanceolate^, Scenedesmus armatus^, Synechocystis sp.	Exogenous indole-3-acetic acid (IAA) improves growth rate in Chlamydomonas reinhardtii^, Chlorella sorokiniana^, Chlorella vulgaris^, Haematococcus pluvialis^, Nostoc sp., Phaeodactylum tricornutum^, and Pleurochrysis carterae^, and oil content in Chlamydomonas reinhardtii^, Haematococcus pluvialis^, and Phaeodactylum ricornutum^*	Elevation of microalgal growth rate, biomass production, oil content, and stress tolerance.	Ashen et al., 1999; Mazur et al., 2001; Sergeeva et al., 2002; Le Bail et al., 2010; Hussain et al., 2010; Maor, 2010; Yokoya et al., 2010; Mazhar et al., 2013; Park et al., 2013; Piotrowska-Niczyporuk and Bajguz, 2014; Stirk et al., 2014
Cytokinins (CK)	Anabaena sp., Calothrix sp., Chlorella minutissima^, Chlorogloeopsis* sp., Chondracanthus^* sp., Chroococcidiopsis sp., Ecklonia^* sp., Ecklonia maxima^, Gelidiums^ sp., Gigartina clathrate^, Gracilaria^ sp., Gracilariopsis^* sp., Hypnea^* sp., Laminaria pallid^, Nannochloropsis oceanic^, Oscillatoria sp., Phormidium sp., Porphyra^* sp., Rhodospirillum^* sp., Synechocystis sp.	Exogenous CK improves cell cycle progression in Nannochloropsis oceanica^; growth rate in Chlamydomonas reinhardtii^, Nannochloropsis oceanica^, and oil content in Chlamydomonas reinhardtii^, Haematococcus pluvialis^, and Phaeodactylum tricornutum^ Elevated temperature led to increase in CK contents in Ecklonia maxima^* and Macrocystis pyrifera^*	Elevation of microalgal growth rate, oil content, and stress tolerance.	Jennings, 1969; Tian et al., 2006; Tsavkelova et al., 2006; Hussain et al., 2010; Stirk et al., 2011; Park et al., 2013; Lu et al., 2014; Stirk et al., 2013, 2014
Ethylene (ET)	Anabaena sp., Calothrix sp., Chlorella pyrenoidosa^, Cylindrospermum* sp., Ecklonia maxima^, Nostoc* sp., Padina arborescent^* sp., Porphyra tenera^, Scytonema* sp., Synechococcus sp.	ET take part in programmed cell death of microalgae in Chlamydomonas reinhardtii^*	Enhancement of microalgal growth rate as well as biomass productivity.	Watanabe and Kondo, 1976; Kreslavsky et al., 1997; Tsavkelova et al., 2006; Yordanova et al., 2010
Gibberellins (GA)	Anabaenopsis sp., Chlamydomonas reinhardtii^, Chlorella^ sp., Cylindrospermum sp., Ecklonia radiate^, Hypnea musciformis^, Nannochloropsis oceanic^, Phormidium foveolarum*	Exogenous GA stimulates astaxanthin biosynthesis in Haematococcus pluvialis^* Exogenous GA improves growth rate in Chlamydomonas reinhardtii^*	Increased algal growth rate and biomass productivity. Target chemical production.	Jennings, 1968; Gupta and Agarwal, 1973; Tsavkelova et al., 2006; Park et al., 2013; Stirk et al., 2013; Voß et al., 2014

Organisms that are eukaryotic algae are designated with “^*” mark.