Melatonin induces nitric oxide and the potential mechanisms relate to innate immunity against bacterial pathogen infection in Arabidopsis

Abstract

Melatonin (N-acetyl-5-methoxytryptamine) is a naturally occurring small molecule, serving as important secondary messenger in the response of plants to various biotic and abiotic stresses. However, the interactions between melatonin and other important molecules in the plant stress response, especially in plant immunity, are largely unknown. In this study, we found that both melatonin and nitric oxide (NO) levels in Arabidopsis leaves were significantly induced by bacterial pathogen (Pst DC3000) infection. The elevated NO production was caused by melatonin as melatonin application enhanced endogenous NO level with great efficacy. Moreover, both melatonin and NO conferred improved disease resistance against Pseudomonas syringe pv. tomato (Pst) DC3000 infection in Arabidopsis. NO scavenger significantly suppressed the rise of NO which was induced by exogenous application of melatonin. As a result, the beneficial effects of melatonin on the expression of salicylic acid (SA)-related genes and disease resistance against bacterial pathogen infection were jeopardized by use of a NO scavenger. Consistently, melatonin application significantly lost its effect on the innate immunity against P. syringe pv. tomato (Pst) DC3000 infection in NO-deficient mutants of Arabidopsis. The results indicate that melatonin-induced NO production is responsible for innate immunity response of Arabidopsis against Pst DC3000 infection.

Exogenous Melatonin Improves Plant Iron Deficiency Tolerance via Increased Accumulation of Polyamine-Mediated Nitric Oxide

“…Although several physiological roles of melatonin in plants have been characterized [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22], regulation of plant Fe deficiency responses and Fe homeostasis by melatonin have not been reported. The present study provided evidence that exogenous melatonin conferred improved plant adaptation to Fe deficiency by promoting Fe remobilization in Arabidopsis plants.…”

“…Meanwhile, a series of adaptive strategies has been evolved to counteract deleterious effects imposed by stressful factors. It has recently been reported that melatonin can increase the resistance of plants to biotic stress via the salicylic acid (SA)- and nitric oxide (NO)-mediated signaling pathways [14,15]. Furthermore, a large number of publications has documented that melatonin positively participates in the alleviation of plant injury by activating endogenous defense systems against various abiotic stresses, such as UV light, cold, heat, drought, and oxidative stress [16,17,18,19,20,21,22], suggesting that melatonin functions as a novel regulator of abiotic stress responses in plants.…”

“…Thus, NO can act as a signaling molecule to regulate plant Fe deficiency responses, and serves as a chelator of Fe. A recent study has reported that exogenous application of melatonin obviously increases endogenous NO levels in Arabidopsis plants [15], although the detailed mechanism behind melatonin regulates cellular NO biosynthesis remains unclear. Shi et al [12] have reported that exogenous melatonin affects polyamine metabolic pathways in oxidative stress-treated Bermuda grass.…”

Melatonin Regulates Root Meristem by Repressing Auxin Synthesis and Polar Auxin Transport in Arabidopsis

“…Numerous studies have shown that melatonin is widely involved in regulating both the biotic and abiotic stress tolerance, biological rhythms, plant growth and development (seed germination, root architecture, shoot development, plant flowering, fruit ripening, and yield; Kang et al, 2010; Okazaki et al, 2010; Wang et al, 2012; Byeon et al, 2013, 2014b; Yin et al, 2013; Zhang et al, 2013, 2014; Zhao et al, 2013; Byeon and Back, 2014a; Shi and Chan, 2014; Weeda et al, 2014; Shi et al, 2015a,b,c,d,e, 2016). …”

A Simple, Rapid Method for Determination of Melatonin in Plant Tissues by UPLC Coupled with High Resolution Orbitrap Mass Spectrometry

“…Moreover, it was reported to be involved in almost all of the plant growth and development stages, from seeds germination to the senescence (Hardeland et al, 2007; Paredes et al, 2009; Arnao and Hernández-Ruiz, 2015; Reiter et al, 2015; Hardeland, 2016). Additionally, many studies have shown that MLT could effectively protect plant tissues from the damage caused by a variety of abiotic and biotic stresses, such as drought stress (Shi et al, 2015b,c), salt stress (Shi et al, 2015b,c), cold stress (Bajwa et al, 2014; Shi et al, 2015b,c), heat stress (Byeon and Back, 2014; Shi et al, 2015d), and pathogen infection (Yin et al, 2013; Shi et al, 2015a). …”