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ARS Home » Southeast Area » Charleston, South Carolina » Vegetable Research » Research » Publications at this Location » Publication #358416

Research Project: Biology, Etiology and Host Resistance in Vegetable Crops to Diseases and Nematodes

Location: Vegetable Research

Title: Role of antioxidant molecule melatonin in plant-host resistance and pathogen suppression in cucurbits

item MANDAL, MIHIR - Oak Ridge Institute For Science And Education (ORISE)
item SUREN, HAKTAN - Virginia Tech
item WARD, BRIAN - Clemson University
item BOROUJERDI, AREZUE - Claflin University
item Kousik, Chandrasekar - Shaker

Submitted to: Cucurbitaceae Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2018
Publication Date: 11/12/2018
Citation: Mandal, M.K., Suren, H., Ward, B., Boroujerdi, A., Kousik, C.S. 2018. Role of Antioxidant Molecule Melatonin in Plant-Host Resistance and Pathogen Suppression in Cucurbits. Presented at Cucurbitaceae 2018, Davis, CA. Curcubitaceae 2018 conference abstracts, Page 11.

Interpretive Summary:

Technical Abstract: Melatonin (N-acetyl-5-methoxytryptamine) is a naturally occurring low molecular weight indole-based metabolite and serves as an antioxidant molecule in various plants and animals. Melatonin, as an animal neurohormone has multi-regulatory effect on patients suffering from insomnia, cancer, Alzheimer’s and other neurobiological disorders. In plants, melatonin plays a wide and diverse range of cellular and physiological functions including plant growth and development, and is inducible in response to diverse biotic and abiotic stresses. However, studies on the direct role of melatonin in disease suppression and as a signaling molecule in host-pathogen defense mechanism are lacking. Our study provides insight into the conserved nature of the biosynthetic pathway of melatonin in watermelon (Citrullus lanatus) and how exogenous application of melatonin, an environmental-friendly immune inducer, can boost plant immunity and suppress pathogen growth. Melatonin (1mM) applied as a spray suppressed powdery mildew development on various cucurbit leaves and Phytophthora fruit rot development on cucumber. Watermelon plants transformed with the melatonin biosynthetic gene SNAT (serotonin N-acetyl transferase) from a powdery mildew resistant plant also helped reduce PM development compared to non-transformed controls. Increased melatonin levels in plants were found to boost resistance against the foliar pathogen Podosphaera xanthii (powdery mildew). Our data also suggests there is subcellular exchange/flow of melatonin intermediates between cytoplasm and chloroplast during melatonin biosynthesis in watermelon. Further, transcriptomic data on melatonin sprayed (1mM) watermelon leaves, suggests that melatonin alters the expression of genes (Pathogenesis related protein PR1a, receptor kinases, NAC domain TFs, Elicitor-responsive protein 3) involved in both PAMP (pathogen-associated molecular pattern) and ETI (effector-triggered immunity) mediated defenses in a salicylic acid (SA) dependent pathway. Developing strategies by using CRISPR/Cas9 genome-editing method to increase melatonin levels in specialty crops such as watermelon and other cucurbit crops can have dual effect: (a) enhanced disease resistance against diverse plant pathogens, (b) serve as a source of natural antioxidant molecules for human nutrition.