Melatonin Induces Disease Resistance to Botrytis cinerea in Tomato Fruit by Activating Jasmonic Acid Signaling Pathway

Abstract

Melatonin acts as a crucial signaling molecule with multiple physiological functions in plant response to abiotic and biotic stresses. However, the impact and regulatory mechanism of melatonin on attenuating tomato fruit fungal decay are unclear. In this study, we investigated the potential roles of melatonin in modulating fruit resistance to Botrytis cinerea and explored related physiological and molecular mechanisms. The results revealed that disease resistance was strongly enhanced by melatonin treatment, and 50 μM was confirmed as the best concentration. Melatonin treatment increased the activities of defense-related enzymes and decreased hydrogen peroxide (H2O2) content with enhanced antioxidant enzyme activities. Moreover, we found that melatonin treatment increased methyl jasmonate (MeJA) content; up-regulated the expressions of SlLoxD, SlAOC, and SlPI II; and reduced the expressions of SlMYC2 and SlJAZ1. We postulated that melatonin played a positive role in tomato fruit resistance to Botrytis cinerea through regulating H2O2 level and JA signaling pathway.

Melatonin and Its Protective Role against Biotic Stress Impacts on Plants

“…Furthermore, results from some investigations support the hypothesis that melatonin increases phagocytic activity and decreases oxidative stress during candidiasis [60][61][62]. In a plant-fungi interaction model, melatonin played a promotional role in the resistance of tomato fruit to Botrytis cinerea via the regulation of H 2 O 2 generation and the jasmonic acid signaling mechanism [63]. Melatonin can increase fungicide susceptibility, enhance vulnerability of Phytophthora infestans to different environmental stress, decrease the dosage level, and promote the efficiency of fungicide treatment against potato late blight [64].…”

Melatonin Is a Potential Target for Improving Post-Harvest Preservation of Fruits and Vegetables

“…A large number of genes, involved in MAPK signaling, nucleotide metabolism, and ethylene biosynthesis, are transcriptionally reprogrammed by melatonin treatment, suggesting the possible role of melatonin as a signal molecule (Xu et al, 2017). Furthermore, exogenous melatonin treatment could promote methyl jasmonate (MeJA) accumulation and enhance the expression of proteinase inhibitor II in tomato fruits, which results in the up-regulation of JA defense signaling that is a crucial pathway in pathogen resistance (Liu et al, 2019). Other studies showed that melatonin is involved in abscisic acid and cytokinin metabolic signaling pathways regulating heat stress response in perennial ryegrass (Zhang et al, 2017a), and participates in adventitious root development by regulating auxin and nitric oxide signaling in tomato plants (Wen et al, 2016).…”

Redox Status, JA and ET Signaling Pathway Regulating Responses to Botrytis cinerea Infection Between the Resistant Cucumber Genotype and Its Susceptible Mutant

“…As the most commonly known members of phytohormones, Jasmonic acid (JA) signaling pathways were reported to have an active effect on inhibiting gray mold ( Liu et al., 2019 ). It was generally believed that activating of JA signaling pathway can induce resistance against necrotrophs ( Liu et al., 2019 ) and endogenous contents of JAs was rapidly up-regulated and then triggered the formation of COI1-JA-JAZ ternary complex to induce degradation of the Jasmonate-ZIM domain (JAZ) proteins ( Zhang et al., 2019 ).…”

“…As the most commonly known members of phytohormones, Jasmonic acid (JA) signaling pathways were reported to have an active effect on inhibiting gray mold ( Liu et al., 2019 ). It was generally believed that activating of JA signaling pathway can induce resistance against necrotrophs ( Liu et al., 2019 ) and endogenous contents of JAs was rapidly up-regulated and then triggered the formation of COI1-JA-JAZ ternary complex to induce degradation of the Jasmonate-ZIM domain (JAZ) proteins ( Zhang et al., 2019 ). The basic helix-loop-helix (bHLH) transcription factor MYC2 acted as a key regulator in the JA signaling pathway ( Boter et al., 2004 ; Lorenzo et al., 2004 ; Dombrecht et al., 2007 ) and transcriptional activity of MYC2 was repressed by JAZ ( Chini et al., 2007 ; Thines et al., 2007 ; Pauwels et al., 2010 ).…”