Roles of Endogenous Melatonin in Resistance to Botrytis cinerea Infection in an Arabidopsis Model

Abstract

Melatonin is an important bioactive molecule in plants. Two synthetases, N-acetylserotonin methyltransferase (ASMT) and serotonin N-acetyltransferase (SNAT) are involved in the final two steps of melatonin synthesis. Melatonin participates in responses to a variety of biotic and abiotic stresses in plants, but few studies have addressed the roles of endogenous melatonin in pathogen resistance. We investigated the role of endogenous melatonin in resistance to Botrytis cinerea infection in an Arabidopsis thaliana model system. Plant lines that overexpressed ASMT or SNAT through genetic manipulation showed upregulated expression of resistance genes PR1 and PR5, transcription factor gene WRKY33, and jasmonic acid (JA) defense pathway marker gene PDF1.2, and downregulated transcription factor gene MYC2 in JA signaling pathway. Higher melatonin content also enhanced the activity of antioxidant enzymes superoxide dismutase (SOD) and peroxidase (POD), increased JA content, reduced plant disease symptoms, and reduced lesion size in leaves. These findings indicate that endogenous melatonin enhances plant resistance to B. cinerea infection. In contrast, ASMT and SNAT gene silencing lines showed opposite results and were more susceptible to B. cinerea. Thus, it can be demonstrated that melatonin functions as an effective regulator of plant stress resistance at the genetic level. A schematic model is presented for its role in resistance to B. cinerea infection. Our findings also helped to elucidate the associated signal transduction pathways and interactions between melatonin and other plant hormones.

Exogenous Melatonin Treatment Induces Disease Resistance against Botrytis cinerea on Post-Harvest Grapes by Activating Defence Responses

“…Among the enzymatic antioxidant defence systems, SOD dismutases O 2 − to O 2 and H 2 O 2 , whereas CAT and POD can convert H 2 O 2 to H 2 O and O 2 in cells [ 55 , 56 ]. Studies had shown that the upregulation of SOD, CAT, and POD activity in the ROS-scavenging system was observed when the resistance response of plants to biotic or abiotic stress occurred [ 47 , 57 , 58 ]. MT treatment can maintain a high scavenging capacity of ROS in cells, which was beneficial to alleviate the extent of membrane lipid peroxidation and preserve the cell membrane integrity [ 59 , 60 ].…”

Identification of Putative Markers of Non-infectious Bud Failure in Almond [Prunus dulcis (Mill.) D.A. Webb] Through Genome Wide DNA Methylation Profiling and Gene Expression Analysis in an Almond × Peach Hybrid Population

“…Its homologous gene in Arabidopsis (AT4G35160, or acetyl serotonin methyltransferase ASMT1 , Berardini et al, 2015 ) has been reported to be expressed in the epidermal L1 layer in the shoot apex. The melatonin biosynthesis pathway was recently shown to be associated with both abiotic ( Wang et al, 2021 ) and biotic ( Zhu et al, 2021 ) stress responses ( Bhowal et al, 2021 ). Members of the melatonin pathway have been shown to be involved in responses to osmotic, drought, and heat stresses ( Bhowal et al, 2021 ), and many of these genes are regulated through miRNAs.…”

Introducing melatonin to the horticultural industry: physiological roles, potential applications, and challenges

“…The role of endogenous melatonin in biotic stress resistance has been investigated in previous studies. A. thaliana that overexpressed ASMT or SNAT showed upregulation of resistance gene expression ( PR1 and PR5 ), increased jasmonic acid (JA) content, smaller lesion size in leaves, and reduced plant disease symptoms [ 90 ].…”