Table 1.
Effect of phytohormones on microalgae lipids and biomass.
| Class | Phytohormone | Species | Stress Condition | Outcome | Reference |
|---|---|---|---|---|---|
| _ | ABA | Chlorella vulgaris | None | Increase in biomass; 1.8-fold increase in lipid content | [83] |
| _ | ABA |
Scenedesmus
quadricauda |
N depletion | 2.1-fold increase in biomass; little effect on lipid content | [84] |
| Auxins | DA | Chlorella ellipsoidea | None | 7.1-fold increase in biomass; increase in overall lipid productivity | [80] |
| Auxins | DA | Dunaliella tertiolecta | Salt stress | 40% biomass increase; lipid content increase from 24 to 70% | [85] |
| Auxins | DA |
Scenedesmus
abundans |
None | 5.4-fold increase in biomass; increase in overall lipid productivity | [80] |
| Auxins | IAA |
Chlorella
sorokiniana |
N depletion | 22% increase in biomass; 49% increase in lipid content | [73] |
| Auxins | IAA |
Chlorella
sorokiniana |
N depletion | 46% increase in biomass; 56% increase in lipid productivity | [74] |
| Auxins | IAA | Chlorella vulgaris | None | No effect on growth, 39% increase in lipid content | [77] |
| Auxins | IAA | Nannochloropsis oceanica | N depletion | 1.5-fold increase in lipid productivity; decrease in SFA and increase in UFA content | [86] |
| Auxins | IAA |
Scenedesmus
quadricauda |
None | Increase in cell growth, biomass, and fatty acid accumulation | [87] |
| Auxins | NAA | Botryococcus braunii | None | Increase in both lipid content and biomass | [76] |
| Brassinosteroid | EB |
Scenedesmus
quadricauda |
None | Increase in cell growth, biomass, and fatty acid accumulation | [87] |
| Cytokinins | BAP | Botryococcus braunii | None | Increase in both lipid content and biomass | [76] |
| Cytokinins | KN | Acutodesmus obliquus | N depletion | 50% increase in biomass productivity; 65% increase in lipid productivity | [72] |
| Cytokinins | KN |
Chlorella
sorokiniana |
N depletion | 36% increase in biomass; 52% increase in lipid productivity | [74] |
| Cytokinins | KN | Desmodesmus sp. | None | 1.5-fold increase in growth rate; 2.5-fold increase in lipid productivity | [88] |
| Cytokinins | ZN | Acutodesmus obliquus | N depletion | 61% increase in biomass productivity; 63% increase in lipid productivity | [72] |
| Ethylene | EP | Botryococcus braunii | None | No effect on biomass; increase in lipid content | [76] |
| Gibberellins | GA | Botryococcus braunii | None | No effect on biomass; increase in lipid content | [76] |
| Gibberellins | GA | Chlorella ellipsoidea | None | 8.7-fold increase in biomass; increase in overall lipid productivity | [80] |
| Gibberellins | GA |
Chlorella
sorokiniana |
N depletion | 36% increase in biomass; 37% increase in lipid productivity | [74] |
| Gibberellins | GA |
Scenedesmus
abundans |
None | 5.3-fold increase in biomass; increase in overall lipid productivity | [80] |
| Jasmonates | JA | Chlorella vulgaris | None | 51% increase in cell density; 54% increase in lipid content | [89] |
| Jasmonates | JA | Chlorella vulgaris | None | Increase in biomass; 2.1-fold increase in lipid content | [83] |
| Jasmonates | MJ | Nannochloropsis oceanica | None | Increase in biomass; 1.4-fold increase in lipid content | [79] |
| Others | DAH |
Chlorella
sorokiniana |
N depletion | 43% increase in biomass; 84% increase in lipid content | [73] |
| Others | DAH | Desmodesmus sp. | None | 1.4-fold increase in growth rate; 2.5-fold increase in lipid productivity | [88] |
| Others | SA | Chlorella vulgaris | None | Increase in biomass; 1.7-fold increase in lipid content | [83] |
| Others | SA | Nannochloropsis oceanica | None | Increase in biomass; 2.2-fold increase in lipid content | [79] |
| Others | SA |
Phaeodactylum
tricornutum |
None | No effect on growth; 29% increase in TGA content | [90] |
| Others | ST | Monoraphidium sp | None | Increase in biomass; 55% increase in lipid productivity | [78] |
Note: In studies where various conditions were evaluated, the outcome reported in the table is the one with the best lipid and biomass productivity. Abbreviations: ABA = abscisic acid; BAP = 6-Benzylaminopurine; DA = 2,4-dichlorophenoxyacetic acid; DAH = diethyl aminoethyl hexanoate; EB = 2,4-epibrassinolide; EP = ethephon; GA = gibberellic acid; IAA = indole-3-acetic acid; JA = jasmonic acid; KN = kinetin; MJ = methyl jasmonate; N = nitrogen; NAA = 1-Naphthaleneacetic acid; SA = salicylic acid; SFA = saturated fatty acid; ST = strigolactone; TGA = triacylglycerols; UFA = unsaturated fatty acids; ZN = zeatin.