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The role of watermelon caffeic acid O-methyltransferase (ClCOMT1) in melatonin biosynthesis and abiotic stress tolerance

Authors :
Zixing Zhang
Jianxiang Ma
Yong Zhang
Yanliang Guo
Jianqiang Yang
Chunhua Wei
Jingyi Yan
Jingjing Chang
Hao Li
Xian Zhang
Li Yuan
Source :
Horticulture Research
Publication Year :
2021
Publisher :
Oxford University Press (OUP), 2021.

Abstract

Melatonin is a pleiotropic signaling molecule that regulates plant growth and responses to various abiotic stresses. The last step of melatonin synthesis in plants can be catalyzed by caffeic acid O-methyltransferase (COMT), a multifunctional enzyme reported to have N-acetylserotonin O-methyltransferase (ASMT) activity; however, the ASMT activity of COMT has not yet been characterized in nonmodel plants such as watermelon (Citrullus lanatus). Here, a total of 16 putative O-methyltransferase (ClOMT) genes were identified in watermelon. Among them, ClOMT03 (Cla97C07G144540) was considered a potential COMT gene (renamed ClCOMT1) based on its high identities (60.00–74.93%) to known COMT genes involved in melatonin biosynthesis, expression in almost all tissues, and upregulation under abiotic stresses. The ClCOMT1 protein was localized in the cytoplasm. Overexpression of ClCOMT1 significantly increased melatonin contents, while ClCOMT1 knockout using the CRISPR/Cas-9 system decreased melatonin contents in watermelon calli. These results suggest that ClCOMT1 plays an essential role in melatonin biosynthesis in watermelon. In addition, ClCOMT1 expression in watermelon was upregulated by cold, drought, and salt stress, accompanied by increases in melatonin contents. Overexpression of ClCOMT1 enhanced transgenic Arabidopsis tolerance against such abiotic stresses, indicating that ClCOMT1 is a positive regulator of plant tolerance to abiotic stresses.

Details

ISSN :
20527276 and 26626810
Volume :
8
Database :
OpenAIRE
Journal :
Horticulture Research
Accession number :
edsair.doi.dedup.....231219cd95e66aa8f09f5cd906afb83b
Full Text :
https://doi.org/10.1038/s41438-021-00645-5