Melatonin and serotonin: Mediators in the symphony of plant morphogenesis

Abstract

Melatonin and serotonin are important signaling and stress mitigating molecules that play important roles across growth and development in plants. Despite many well-documented responses, a systematic investigation of the entire metabolic pathway (tryptophan, tryptamine, and N-acetylserotonin) does not exist, leaving many open questions. The objective of this study was to determine the responses of Hypericum perforatum (L.) to melatonin, serotonin, and their metabolic precursors. Two well-characterized germplasm lines (#4 and 112) created by mutation and a haploid breeding program were compared to wild type to identify specific responses. Germplasm line 4 has lower regenerative and photosynthetic capacity than either wild type or line 112, and there are documented significant differences in the chemistry and physiology of lines 4 and 112. Supplementation of the culture media with tryptophan, tryptamine, N-acetylserotonin, serotonin, or melatonin partially reversed the regenerative recalcitrance and growth impairment of the germplasm lines. Quantification of phytohormones revealed crosstalk between the indoleamines and related phytohormones including cytokinin, salicylic acid, and abscisic acid. We hypothesize that melatonin and serotonin function in coordination with their metabolites in a cascade of phytochemical responses including multiple pathways and phytohormone networks to direct morphogenesis and protect photosynthesis in H. perforatum.

PTEN inhibition attenuates endothelial cell apoptosis in coronary heart disease via modulating the AMPK–CREB–Mfn2‐mitophagy signaling pathway

“…However, the role of mitophagy in ox‐LDL‐mediated endothelial cell dysfunction remains unknown. Based on the findings of previous studies (Erland, Shukla, Singh, Murch, & Saxena, ), mitophagy is activated by Mitofusin‐2 (Mfn2) and helps injured mitochondria fuse with the lysosome (Chandra et al, ), ensuring mitophagy activation in LPS‐related inflammatory injuries (Escors et al, ). Furthermore, other studies have also indicated that Mfn2 is primarily activated by the AMPK pathway (Daniel et al, ), which increases the phosphorylation of CREB, a transcriptional promoter (Edwards et al, ).…”

Melatonin‐deficient rice plants show a common semidwarf phenotype either dependent or independent of brassinosteroid biosynthesis

“…Melatonin is essential for normal growth and development, such as stomatal closure, the auxin signaling pathway, starch synthesis, plant regeneration, and root formation, as well as for defense against an array of biotic and abiotic stressors, including high light, pathogens, salt, senescence, and high temperature, among others . The functional roles of melatonin in plants are associated with crosstalk with plant hormones, such as auxin, cytokinin, salicylic acid, and abscisic acid …”

PR‐10 proteins as potential mediators of melatonin‐cytokinin cross‐talk in plants: crystallographic studies of LlPR‐10.2B isoform from yellow lupine

“…We were able to crystallize LlPR‐10.2B in complex with melatonin (LlPR‐10.2B/MEL, M) and as a mixed complex with melatonin and trans ‐zeatin (LlPR‐10.2B/MEL/ZEA, MZ), and present the crystal structures of these complexes together with a discussion of possible involvement of PR‐10 proteins in melatonin binding in plants. Our results are particularly exciting in view of the recent findings that melatonin is able to increase trans ‐zeatin levels in plants; the complexes of LlPR‐10.2B could provide an explanation of the molecular basis for this phenomenon. Moreover, our results not only confirm the binding between the two functionally correlated partners, LlPR‐10.2B and melatonin, but also reveal that the protein is either able to specifically bind an unidentified product of melatonin transformation or itself promotes this transformation.…”