Application of Exogenous Melatonin Improves Tomato Fruit Quality by Promoting the Accumulation of Primary and Secondary Metabolites

Abstract

Melatonin plays key roles in improving fruit quality and yield by regulating various aspects of plant growth. However, the effects of how melatonin regulates primary and secondary metabolites during fruit growth and development are poorly understood. In this study, the surfaces of tomato fruit were sprayed with different concentrations of melatonin (0, 50, and 100 µmol·L−1) on the 20th day after anthesis; we used high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) to determine the changes in primary and secondary metabolite contents during fruit development and measured the activity of sucrose metabolizing enzymes during fruit development. Our results showed that 100 µmol·L−1 melatonin significantly promoted the accumulation of soluble sugar in tomato fruit by increasing the activities of sucrose synthase (SS), sucrose phosphate synthase (SPS), and acid convertase (AI). The application of 100 µmol·L−1 melatonin also increased the contents of ten amino acids in tomato fruit as well as decreased the contents of organic acids. In addition, 100 µmol·L−1 melatonin application also increased the accumulation of some secondary metabolites, such as six phenolic acids, three flavonoids, and volatile substances (including alcohols, aldehydes, and ketones). In conclusion, melatonin application improves the internal nutritional and flavor quality of tomato fruit by regulating the accumulation of primary and secondary metabolites during tomato fruit ripening. In the future, we need to further understand the molecular mechanism of melatonin in tomato fruit to lay a solid foundation for quality improvement breeding.

Improvement of Tomato Performance Under Low Temperature Stress Using Some Bio-Stimulants Compared With Low Tunnel System

“…The foliar application with acetyl salicylic acid reduced the titratable acidity (Meena et al, 2017), also potassium silicate reduced titratable acidity under chilling conditions (Alkharpotly and Abdelrasheed, 2021). Dou et al (2022) reported that exogenous melatonin application clearly reduced the acidity content in tomato fruits.…”

Melatonin Modulates Tomato Root Morphology by Regulating Key Genes and Endogenous Hormones

“…Primarily, melatonin has been extensively researched for its role in enhancing tomato resistance to various abiotic stresses, encompassing drought [41,42], heavy metals [43,44], heat damage [45], cold damage [46], salt damage [47], and more. Furthermore, the melatonin treatment of tomatoes has been found to delay leaf senescence [48], boost tomato disease resistance [49,50], and improve tomato fruit quality [51,52]. Concurrently, research has revealed that melatonin treatment can induce the accumulation of nitric oxide (NO) and influence the development of adventitious roots in tomato seedlings [37].…”

Melatonin imparts tolerance to combined drought and high-temperature stresses in tomato through osmotic adjustment and ABA accumulation

“…Plants themselves possess a mechanism to perceive signals, communicate, and respond to various abiotic stress factors, which are mediated by phytohormones ( Davies, 2010 ). A pleiotropic molecule, melatonin, has a significant role in mitigating the detrimental effects of abiotic stress, involving growth and development ( Liang et al., 2019 ), seed germination ( Castanares and Bouzo, 2019 ), root architecture ( Altaf et al., 2022 ), photosynthesis and antioxidant defense ( Anitha et al., 2023 ), stomatal regulation ( Jensen et al., 2023 ), and fruit yield and quality ( Dou et al., 2022 ). Several findings have investigated the effect of melatonin on physiological and biochemical mechanisms under individual drought or HT stresses ( Ibrahim et al., 2020 ; Jahan et al., 2021 ).…”