The influences of phytohormones on triacylglycerol accumulation in an oleaginous marine diatom Phaeodactylum tricornutum
Environmental stresses such as nitrate deprivation and high light are effective at increasing lipid content in microalgae, but they can also slow down and even stop growth. In this study, the phytohormones methyl jasmonate, salicylic acid, gibberellin, abscisic acid, and ethephon were introduced to cultures of the oleaginous marine diatom Phaeodactylum tricornutum in an attempt to increase growth and lipid production. Single-factor experiments showed that the influences of some of the phytohormones were closely related to their concentrations. Methyl jasmonate, abscisic acid, and salicylic acid promoted P. tricornutum growth and lipid accumulation at certain concentrations. The differing effects of the three phytohormones on P. tricornutum may be related to the respective phytohormone’s responsive cis-regulatory elements in the upstream regions of the triacylglycerol (TAG) synthesis genes. Methyl jasmonate, abscisic acid, and salicylic acid were further studied in response surface experiments, through which a 141% increase in TAG production was attained for 10-L cultures of P. tricornutum grown under optimal conditions. This study suggests that some phytohormones can promote P. tricornutum lipid accumulation without hindering growth. It also provides another strategy for improving the production of microalgae for use as biodiesel.
KeywordsPhaeodactylum tricornutum Triacylglycerol Phytohormones Single-factor experiments Response surface experiments
We would like to acknowledge with apologies many excellent studies that could not be cited due to space limitations. We are grateful to the anonymous reviewers for their valuable improvement to this manuscript. We thank Natalie Kim, PhD, from Liwen Bianji, Edanz Editing, China (www.liwenbianji.cn/ac), for editing the English text of a draft of this manuscript.
This research was supported by the National Key Research and Development Program of China (2016YFB0601001), the Science and Technology Service Network Initiative of the Chinese Academy of Sciences (KFJ-STS-ZDTP-023), the Project of Innovation & Development of Marine Economy (HHCL201803), the seed project of Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences(YIC755031013).
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