Melatonin-induced plant adaptation to cadmium stress involves enhanced phytochelatin synthesis and nutrient homeostasis in Solanum lycopersicum L

• Published in: Journal of hazardous materials Vol. 456; p. 131670
• Main Authors: Xing, Qufan, Hasan, Md. Kamrul, Li, Zhichao, Yang, Ting, Jin, Weiduo, Qi, Zhenyu, Yang, Ping, Wang, Guanghui, Ahammed, Golam Jalal, Zhou, Jie
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.08.2023
• Subjects: Cadmium - toxicity; Cadmium stress; Homeostasis; Hydrogen Peroxide; Melatonin; Melatonin - pharmacology; Nutrient absorption; Osmotic equilibrium; Phytochelatin; Phytochelatins; Plants; Redox homeostasis; Solanum lycopersicum; Cadmium stress; Melatonin; Redox homeostasis; Phytochelatin; Nutrient absorption; Osmotic equilibrium
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.131670

Cadmium (Cd) pollution is an increasingly serious problem in crop production. Although significant progress has been made to comprehend the molecular mechanism of phytochelatins (PCs)-mediated Cd detoxification, the information on the hormonal regulation of PCs is very fragmentary. In the present study, we constructed TRV-COMT, TRV-PCS, and TRV-COMT-PCS plants to further assess the function of CAFFEIC ACID O-METHYLTRANSFERASE (COMT) and PHYTOCHELATIN SYNTHASE (PCS) in melatonin-induced regulation of plant resistance to Cd stress in tomato. Cd stress significantly decreased chlorophyll content and CO2 assimilation rate, but increased Cd, H2O2 and MDA accumulation in the shoot, most profoundly in PCs deficient TRV-PCS and TRV-COMT-PCS plants. Notably, Cd stress and exogenous melatonin treatment significantly increased endogenous melatonin and PC contents in non-silenced plants. Results also explored that melatonin could alleviate oxidative stress and enhance antioxidant capacity and redox homeostasis by conserving improved GSH:GSSG and ASA:DHA ratios. Moreover, melatonin improves osmotic balance and nutrient absorption by regulating the synthesis of PCs. This study unveiled a crucial mechanism of melatonin-regulated PC synthesis, persuaded Cd stress tolerance and nutrient balance in tomato, which may have potential implications for the enhancement of plant resistance to toxic heavy metal stress. [Display omitted] •Role of melatonin (MT) and phytochelatins (PCs) in Cd tolerance was studied in tomato.•Silencing of COMT, PCS, and COMT-PCS aggravated Cd phytotoxicity in tomato plants.•MT alleviated oxidative stress and enhanced antioxidant defense and redox homeostasis.•MT improved osmotic balance and nutrient absorption by regulating PC synthesis.•PHYTOCHELATIN SYNTHASE (PCS) partly acts downstream of COMT to confer Cd tolerance.