Melatonin is required for H₂O₂‐ and NO‐mediated defense signaling through MAPKKK3 and OXI1 in Arabidopsis thaliana

Abstract

Melatonin influences plant innate immunity through the mitogen-activated protein kinase (MAPK) pathway. However, the most upstream MAPK component in melatonin signaling and the dependence of generation of a reactive oxygen species (ROS) burst on melatonin synthesis and signaling remain unclear. In this study, treatment of several mekk (alias mapkkk)-knockout Arabidopsis mutants with melatonin revealed that the MAPKKK3 and OXI1 (oxidative signal-inducible1) kinases are responsible for triggering melatonin-induced defense signaling pathways. In addition, melatonin induction upon infection with the avirulent pathogen Pseudomonas syringae DC3000 (avrRpt2) was independent of H O and NO individually, but dependent on the combination of H O and NO. Moreover, melatonin-mediated induction of the expression of defense-related genes, such as PR1 and ICS1, was not altered in the H O -deficient rbohD/F-knockout mutant cotreated with an NO scavenger, indicating that melatonin functions downstream of the ROS and NO burst. Collectively, the data indicate that melatonin-mediated induction of an innate immune response requires multiple signaling molecules and activation of MAPKKK3 and OXI1, followed by triggering of downstream MAPK cascades, such as MAPK3 and MAPK6.

Overexpression of rice serotonin N‐acetyltransferase 1 in transgenic rice plants confers resistance to cadmium and senescence and increases grain yield

“…Later, cadmium was shown to be the most effective inducer of melatonin synthesis in rice plants via increases in transcription of TDC1 , T5H , and ASMT1 . The effect of cadmium on melatonin induction may be attributed to the oxidative induction of both H 2 O 2 and NO, which were recently shown to be indispensable signaling molecules for melatonin synthesis in Arabidopsis . Hasan et al .…”

“…Since the first discovery of melatonin in plants in 1995, many pharmacological studies have been performed to investigate its functional and physiological significance . Large numbers of experiments involving exogenous application of melatonin to a series of plant species indicated that melatonin acts as a biostimulator in plants by enhancing a myriad of defense responses against abiotic stresses, including oxidative stress, high temperature, cold, senescence, drought, and salt, as well as biotic stress such as pathogen attacks . In addition to the defense responses, melatonin has also been implicated in promoting plant growth processes, such as seedling growth, flowering, nutrient absorption, and fruit ripening, suggesting a potential role of melatonin as a plant growth factor .…”

RAV transcription factors are essential for disease resistance against cassava bacterial blight via activation of melatonin biosynthesis genes

“…In recent years, melatonin ( N ‐acetyl‐5‐methoxytryptamine) was widely shown to be extensively involved in plant development processes and stress responses . At least, 3 research groups have contributed significant information in melatonin‐mediated plant immunity . These groups highlighted the protective effect of melatonin on conferring improved disease resistance in Arabidopsis .…”

Hyperglycaemia Stress-Induced Renal Injury is Caused by Extensive Mitochondrial Fragmentation, Attenuated MKP1 Signalling, and Activated JNK-CaMKII-Fis1 Biological Axis

“…SP600125 (SP), a JNK pathway blocker, was added to hyperglycaemia-treated cells [46], which was used as the negative control group. Meanwhile, Anisomycin (Ani), a JNK pathway agonist, was administered to MKP1-overexpressing cells, which was used as the positive control group [47]. After blockade of JNK pathway in hyperglycaemia-treated cells, JNK phosphorylation was downregulated, accompanied with a drop in CaMKII phosphorylation and Fis1 expression (Fig.…”