Synergistic Effects of Melatonin and Gamma-Aminobutyric Acid on Protection of Photosynthesis System in Response to Multiple Abiotic Stressors

Aida Shomali,Edyta Sierka,Mohammad Mohammadian,Mehdi Seif,Sasan Aliniaeifard,Mahmoud Lotfi,Hazem M Kalaji,Fardad Didaran,Wacław Roman Strobel

doi:10.3390/cells10071631

Abstract

GABA (gamma-aminobutyric acid) and melatonin are endogenous compounds that enhance plant responses to abiotic stresses. The response of Vicia faba to different stressors (salinity (NaCl), poly ethylene glycol (PEG), and sulfur dioxide (SO2)) was studied after priming with sole application of GABA and melatonin or their co-application (GABA + melatonin). Both melatonin and GABA and their co-application increased leaf area, number of flowers, shoot dry and fresh weight, and total biomass. Plants treated with GABA, melatonin, and GABA + melatonin developed larger stomata with wider aperture compared to the stomata of control plants. The functionality of the photosynthetic system was improved in primed plants. To investigate the photosynthetic functionality in details, the leaf samples of primed plants were exposed to different stressors, including SO2, PEG, and NaCl. The maximum quantum yield of photosystem II (PS II) was higher in the leaf samples of primed plants, while the non-photochemical quenching (NPQ) of primed plants was decreased when leaf samples were exposed to the stressors. Correlation analysis showed the association of initial PIabs with post-stress FV/FM and NPQ. Stressors attenuated the association of initial PIabs with both FV/FM and NPQ, while priming plants with GABA, melatonin, or GABA + melatonin minimized the effect of stressors by attenuating these correlations. In conclusion, priming plants with both GABA and melatonin improved growth and photosynthetic performance of Vicia faba and mitigated the effects of abiotic stressors on the photosynthetic performance.

Highlights

IntroductionVarious approaches have been employed for enhancing plant tolerance to abiotic stresses; some of those approaches are tedious (e.g., conventional breeding), and some are controversial (e.g., plant genetic modification) [4]
The concentration of GABA and melatonin was selected according to the optimum concentration of GABA and melatonin that were reported to have a positive effect on plant abiotic stress tolerance [57,58,59]
Considering higher non-photochemical quenching (NPQ) in primed plants when exposed to stresses, a role for priming agents in improving energy dissipation as a protective mechanism is conclusive

Summary

Introduction

Various approaches have been employed for enhancing plant tolerance to abiotic stresses; some of those approaches are tedious (e.g., conventional breeding), and some are controversial (e.g., plant genetic modification) [4] Considering these limitations, attentions are directed toward priming of plants to improve their stress tolerance. Priming of plants can be initiated naturally when non-lethal stresses come about, that is, associated with the promotion of tolerance mechanisms [5,6,7], which diminishes the negative impact of stress factor on growth and physiological responses of plants. Both biotic and abiotic agents have been used for priming of plants. Some example of those are phytohormones such as polyamines [12] and salicylic acid [13,14], mild stress pre-exposure such as different salts [13] and reactive oxygen species [3]

Methods

Results

Discussion

Conclusion