Understanding the mechanism of red light-induced melatonin biosynthesis facilitates the engineering of melatonin-enriched tomatoes

Abstract

Melatonin is a functionally conserved broad-spectrum physiological regulator found in most biological organisms in nature. Enrichment of tomato fruit with melatonin not only enhances its agronomic traits but also provides extra health benefits. In this study, we elucidate the full melatonin biosynthesis pathway in tomato fruit by identifying biosynthesis-related genes that encode caffeic acid O-methyltransferase 2 (SlCOMT2) and N-acetyl-5-hydroxytryptamine-methyltransferases 5/7 (SlASMT5/7). We further reveal that red light supplementation significantly enhances the melatonin content in tomato fruit. This induction relies on the “serotonin—N-acetylserotonin—melatonin” biosynthesis route via the SlphyB2-SlPIF4-SlCOMT2 module. Based on the regulatory mechanism, we design a gene-editing strategy to target the binding motif of SlPIF4 in the promoter of SlCOMT2, which significantly enhances the production of melatonin in tomato fruit. Our study provides a good example of how the understanding of plant metabolic pathways responding to environmental factors can guide the engineering of health-promoting foods.

Novel melatonin‐producing Bacillus safensis EH143 mitigates salt and cadmium stress in soybean

“…The serotonin undergoes acetylation and is converted to N-acetyl-serotonin, which, upon methylation, synthesizes melatonin as a final product. 60 Based on this knowledge, the basic steps involved in melatonin synthesis of EH143 in our analysis seem to be aligned with that observed in plant and animal systems. This is reinforced by our findings of several genes related to tryptophan production and utilization in the whole genome sequence of EH143 (Figure 1D).…”

“…In plants, melatonin synthesis begins with the conversion of l ‐tryptophan to tryptamine in the cytoplasm; which is catalyzed by tryptamine‐5‐hydroxylase (T5H); then, tryptamine is converted to serotonin, which is facilitated by acetyl‐coenzyme A (Ac‐CoA). The serotonin undergoes acetylation and is converted to N‐acetyl‐serotonin, which, upon methylation, synthesizes melatonin as a final product 60 . Based on this knowledge, the basic steps involved in melatonin synthesis of EH143 in our analysis seem to be aligned with that observed in plant and animal systems.…”

Photoperiod-Dependent Nutrient Accumulation in Rice Cultivated in Plant Factories: A Comparative Metabolomic Analysis

“…Furthermore, numerous studies have shown that a diversely colored light spectrum have broad regulatory effects on metabolism [20,21]. Supplementing red light significantly triggers melatonin accumulation in tomatoes, improves agronomic traits, and provides additional health advantages [22]. Among the factors influenced by light, an appropriate photoperiod can promote the accumulation of metabolites [23].…”

Genome editing based on <i>in vitro</i>-assembled ribonucleoproteins in plants

“…For example, targeted editing of genes related to drought tolerance in plants has shown promising results in enhancing plantsʼ resilience to drought stress (Li et al 2022). In addition, gene editing technology can be applied to modify the metabolic pathways of medicinal or cash crops to increase the yields of bioactive compounds (Zhang et al 2023).…”