Overexpression of TaCOMT Improves Melatonin Production and Enhances Drought Tolerance in Transgenic Arabidopsis

Abstract

Melatonin (N-acetyl-5-methoxytryptamine) is involved in many developmental processes and responses to various abiotic stresses in plants. Most of the studies on melatonin focus on its functions and physiological responses in plants, while its regulation mechanism remains unknown. Caffeic acid 3-O-methyltransferase (COMT) functions at a key step of the biosynthesis process of melatonin. In this study, a COMT-like gene, TaCOMT (Traes_1AL_D9035D5E0.1) was identified in common wheat (Triticum aestivum L.). Transient transformation in wheat protoplasts determined that TaCOMT is localized in cytoplasm. TaCOMT in wheat was induced by drought stress, gibberellin (GA)3 and 3-Indoleacetic acid (IAA), but not by ABA. In TaCOMT transgenic Arabidopsis, melatonin contents were higher than that in wild type (WT) plants. Under D-Mannitol treatment, the fresh weight of the transgenic Arabidopsis was significantly higher than WT, and transgenic lines had a stronger root system compared to WT. Drought tolerance assays in pots showed that the survival rate of TaCOMT-overexpression lines was significantly higher than that of WT lines. this phenotype was similar to that the WT lines treated with melatonin under drought condition. In addition, the TaCOMT transgenic lines had higher proline content and lower malondialdehyde (MDA) content compared to WT lines after drought treatment. These results indicated that overexpression of the wheat TaCOMT gene enhances drought tolerance and increases the content of melatonin in transgenic Arabidopsis. It could be one of the potential genes for agricultural applications.

Nano-ZnO-Induced Drought Tolerance Is Associated with Melatonin Synthesis and Metabolism in Maize

“…In addition, serotonin can be also catalyzed by COMT to produce 5-methoxytryptamine, which is further converted into melatonin. The overexpression of TaCOMT enhances drought resistance in transgenic Arabidopsis via increasing the melatonin and proline levels and decreasing MDA concentration [63]. Further, COMT contributed to stem mechanical strength by enhancing lignin synthesis, which also benefited the drought tolerance in maize [64].…”

Exogenous melatonin enhances salt stress tolerance in tomato seedlings

“…The beneficial role of melatonin has been proved by increasing number of reports. The useful role of this magic molecule has been confirmed in many plant processes including germination of seeds and seedling growth (Aguilera et al 2015, germplasm storage (Zhao et al 2011, Uchendu et al 2013, development and growth of roots (Hernandez-Ruiz et al 2005, Park andBack 2012); and in responses to many stress conditions including high temperature stress (Jahan et al 2019), salt stress (Liu et al 2019, Li et al 2019c, drought stress (Wang et al 2013, Yang et al 2019b, cold stress (Bajwa et al 2014, heavy metals (Kaya et al 2019), pathogens (Wei et al 2017), and ultraviolet radiation (Afreen et al 2006, Wei et al 2019. Melatonin has multiple functions in plants, though, its possible role under abiotic stresses is still uncertain (Siddiqui et al 2019).…”

Melatonin Alleviates Drought Stress by a Non-Enzymatic and Enzymatic Antioxidative System in Kiwifruit Seedlings

“…(3) melatonin induces the transcriptional level of the mitogen-activated protein kinase (MAPK) signaling pathway and its main components (transcription factors, including WRKY, DREB, MYB, and NAC) upregulation, which are responsible for drought stress tolerance [13,24,27]; and (4) melatonin provides drought tolerance by regulating phytohormone metabolism pathways. Melatonin promotes drought stress tolerance by suppressing indoleacetic acid (IAA) biosynthesis via GA signaling, stimulating cytokinin (CK) biosynthesis, and reducing abscisic acid (ABA) accumulation [18,21,24,27,28]. The results of our previous study indicated that exogenous melatonin can effectively improve the repression of biomass accumulation and photosynthesis caused by drought stress [25].…”