Strigolactone mediates jasmonic acid-induced lipid production in microalga Monoraphidium sp. QLY-1 under nitrogen deficiency conditions.

The roles of jasmonic acid (JA) in the regulation of cell growth and lipid biosynthesis under the combination of strigolactone (SL) treatment and nitrogen deficiency (ND) were investigated. In this work, the optimised ND condition (46.18%) and ND combined with SL treatment (53.71%) showed 1.11- and 1.29-fold increases in lipid content in Monoraphidium sp. QLY-1 compared with the control condition (41.57%). The levels of JA, glutathione (GSH), and γ-aminobutyric acid (GABA) and lipogenic genes expression were upregulated by the combination of SL and ND, but the ROS level was decreased. Furthermore, exogenous JA supplementation induced the highest lipid content (57.12%) and productivity (312.35 mg L d) under ND combined with SL treatment. This study provided a combined strategy for enhancing lipid production and supplied novel insights into the role of JA signalling in regulating lipid synthesis and oxidative stress in microalgae by combining SL treatment with ND.