Maize PHYTOMELATONIN RECEPTOR1 functions in plant tolerance to osmotic and drought stress

Abstract

Phytomelatonin is a universal signal molecule that regulates plant growth and stress response. However, only one receptor, AtPMTR1/CAND2 that could directly bind with and perceive melatonin signaling has been identified in dicotyledon plant Arabidopsis so far, whether other plants contain phytomelatonin receptor and how it functions are still unknown. Herein, we identified a new phytomelatonin receptor from monocot maize, and investigated its role in plant osmotic and drought stress response. Using homology searching, maize plasma membrane-localized Zm00001d034063/ZmPMTR1 protein with strong binding activity to melatonin was identified as a potential phytomelatonin receptor in maize. Overexpressing ZmPMTR1 promoted osmotic stress tolerance of the wild-type Arabidopsis plant, and rescued osmotic stress sensitivity of the Arabidopsis cand2-1 mutant. Moreover, ZmPMTR1 largely rescued defect of melatonin-induced stomatal closure in the cand2-1 mutant, thereby reducing water loss rate and increasing drought stress tolerance. Furthermore, we identified a maize mutant of ZmPMTR1, EMS4-06e2fl with a point mutation causing premature termination of protein translation, and found that this maize mutant had lower leaf temperature, increased water loss rate and enhanced drought stress sensitivity. Collectively, our study reveals that ZmPMTR1, as the first identified and analyzed phytomelatonin receptor in monocot plant, functions necessarily in maize plant drought stress tolerance.

Crosstalk between Melatonin and Reactive Oxygen Species in Plant Abiotic Stress Responses: An Update

“…Several studies take the important stance that the transmembrane receptor of melatonin (PMTR1/CAND2) is found in Arabidopsis , tobacco, alfalfa, and maize [ 116 , 117 , 118 , 119 ]. It is also located in the plasma membrane, and can interact with G-protein α subunits, thereby activating RBOHs to promote stomatal closure in Arabidopsis ( Figure 2 ) [ 116 , 119 ]. Melatonin inhibits endogenous NO accumulation and reduces the S-nitrosylation of RBOH to activate the ROS signaling pathway [ 99 ].…”

Mammalian Melatonin Agonist Pharmaceuticals Stimulate Rhomboid Proteins in Plants

“…Understanding signalling mechanisms of MEL in plants has enormous implications for our understanding of plant responses to their environments. The search for MEL interacting proteins in plants has led to one MEL receptor, PMTR1, which, to date, has been identified in Arabidopsis and maize [ 7 , 8 ], although some concerns exist as to the whether the protein represents a bona fide receptor or whether it is a melatonin interacting protein [ 38 ]. Several downstream mediators have been proposed [ 39 ]; however, the initial steps in the plant MEL signalling cascade remain elusive.…”

“…Recently, the first phytomelatonin receptor, PMTR-1, has been proposed in Arabidopsis thaliana (L.) Heynh. stomata, for which a homolog has since been characterized in maize ( Zea mays L.) [ 7 , 8 ]. MEL mediates diverse plant growth, developmental and survival processes throughout the plant life cycle [ 9 , 10 ].…”

The phytomelatonin receptor PMTR1 regulates seed development and germination by modulating abscisic acid homeostasis in Arabidopsis thaliana

“…20,21 Recently, putative MLT receptors also have been identified in Medicago sativa and maize, and they are proved to be involved in salinity, osmotic, and drought, respectively. 22,23 Beyond its role as a plant hormone, MLT also has been considered as an important regulator with diverse physiological functions in plant growth and development, due to its potential to modulate the expression of remarkable gene elements. 8 For example, MLT regulates the expression of the elements related to secondary metabolism, plant hormones biosynthesis, and catabolism.…”

“…PMTR1 was reported to function in governing the receptor‐dependent stomatal closure and osmotic stress tolerance 20,21 . Recently, putative MLT receptors also have been identified in Medicago sativa and maize, and they are proved to be involved in salinity, osmotic, and drought, respectively 22,23 …”