Synergistic Effect of Melatonin and Selenium Improves Resistance to Postharvest Gray Mold Disease of Tomato Fruit

Abstract

Melatonin (MT) is a ubiquitous hormone molecule that is commonly distributed in nature. MT not only plays an important role in animals and humans but also has extensive functions in plants. Selenium (Se) is an essential micronutrient for animals and humans, and is a beneficial element in higher plants at low concentrations. Postharvest diseases caused by fungal pathogens lead to huge economic losses worldwide. In this study, tomato fruits were treated with an optimal sodium selenite (20 mg/L) and melatonin (10 μmol/L) 2 h and were stored for 7 days at room temperature simulating shelf life, and the synergistic effects of Se and MT collectively called Se-Mel on gray mold decay in tomato fruits by Botrytis cinerea was investigated. MT did not have antifungal activity against B. cinerea in vitro, while Se significantly inhibited gray mold development caused by B. cinerea in tomatoes. However, the interaction of MT and Se showed significant inhibition of the spread and growth of the disease, showing the highest control effect of 74.05%. The combination of MT with Se treatment enhanced the disease resistance of fruits by improving the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as increasing the gene expression level of pathogenesis-related (PR) proteins. Altogether, our results indicate that the combination of MT and Se would induce the activation of antioxidant enzymes and increase the expression of PR proteins genes that might directly enhance the resistance in tomato fruit against postharvest pathogenic fungus B. cinerea.

Melatonin targets MoIcl1 and works synergistically with fungicide isoprothiolane in rice blast control

“…Similarly, the dosage of ethylicin can be reduced by 10‐fold when supplemented with melatonin in inhibiting vegetative growth of Phytophthora nicotianae , the causal agent of oomycetic black shank disease in tobacco 82 . Multiple other examples have been reported in agriculture and medicine on the synergy of melatonin with various other drugs 33,35,83 . The possible other fungicides synergistic with melatonin can be predicted 80 .…”

“…82 Multiple other examples have been reported in agriculture and medicine on the synergy of melatonin with various other drugs. 33,35,83 The possible other fungicides synergistic with melatonin can be predicted. 80 Melatonin and isoprothiolane may co-suppress related biological processes through overlapping targets, supported by our transcriptomic results that 1111 DEGs are common in the three treatment groups, and similar synergistic mechanisms have been reported for berberine and eugenol that synergistically depolarize mitochondrial membranes of yeast.…”

“…32 The synergistic effects of melatonin and various drugs have been reported in cancer treatment and disease management. [33][34][35][36][37][38] Melatonin combined with vincristine or ifosfamide has a synergistic effect in inhibiting Ewing sarcoma 33 ; melatonin and selenium synergistically inhibit the growth of the fungal pathogen Botrytis cinerea. 35 In this study, we demonstrated that the synergy of melatonin and isoprothiolane inhibited the growth of M. oryzae.…”

“…[33][34][35][36][37][38] Melatonin combined with vincristine or ifosfamide has a synergistic effect in inhibiting Ewing sarcoma 33 ; melatonin and selenium synergistically inhibit the growth of the fungal pathogen Botrytis cinerea. 35 In this study, we demonstrated that the synergy of melatonin and isoprothiolane inhibited the growth of M. oryzae. Melatonin and isoprothiolane not only had synergistic inhibitory effects on development but also plant infection by M. oryzae.…”

“…For example, combined application of a biocontrol agent TA‐1 and fungicide fluopimomide synergistically improves the control of gray mold in tomato 32 . The synergistic effects of melatonin and various drugs have been reported in cancer treatment and disease management 33–38 . Melatonin combined with vincristine or ifosfamide has a synergistic effect in inhibiting Ewing sarcoma 33 ; melatonin and selenium synergistically inhibit the growth of the fungal pathogen Botrytis cinerea 35 …”