Methyl Jasmonate Protects the PS II System by Maintaining the Stability of Chloroplast D1 Protein and Accelerating Enzymatic Antioxidants in Heat-Stressed Wheat Plants.

Mehar Fatma,Noushina Iqbal,Nafees A. Khan,Prashant Kaushik,Parvaiz Ahmad,Zebus Sehar,Mohammed Nasser Alyemeni

doi:10.3390/antiox10081216

Mehar Fatma, Noushina Iqbal + Show 5 more

Open Access

https://doi.org/10.3390/antiox10081216

Copy DOI

Abstract

The application of 10 µM methyl jasmonate (MeJA) for the protection of wheat (Triticum aestivum L.) photosystem II (PS II) against heat stress (HS) was studied. Heat stress was induced at 42 °C to established plants, which were then recovered at 25 °C and monitored during their growth for the study duration. Application of MeJA resulted in increased enzymatic antioxidant activity that reduced the content of hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances (TBARS) and enhanced the photosynthetic efficiency. Exogenous MeJA had a beneficial effect on chlorophyll fluorescence under HS and enhanced the pigment system (PS) II system, as observed in a JIP-test, a new tool for chlorophyll fluorescence induction curve. Exogenous MeJA improved the quantum yield of electron transport (ETo/CS) as well as electron transport flux for each reaction center (ET0/RC). However, the specific energy fluxes per reaction center (RC), i.e., TR0/RC (trapping) and DI0/RC (dissipation), were reduced by MeJA. These results indicate that MeJA affects the efficiency of PS II by stabilizing the D1 protein, increasing its abundance, and enhancing the expression of the psbA and psbB genes under HS, which encode proteins of the PS II core RC complex. Thus, MeJA is a potential tool to protect PS II and D1 protein in wheat plants under HS and to accelerate the recovery of the photosynthetic capacity.

Highlights

Wheat is the main cereal crop belonging to the Poaceae family, which contributes 30%and 50% to the world grain production and grain trade, respectively [1]
The present study shows that exogenous methyl jasmonate (MeJA) markedly increased the activity of the antioxidant enzymes CAT and ascorbate peroxidase (APX), which led to efficient detoxification of reactive oxygen species (ROS) and decreased lipid peroxidation in membranes under stress
The results showed that the electron transportation efficiency and the function of Chl in photosystem II (PS II) decreased under heat stress, but the application of MeJA remarkably improved ET0 /reaction center (RC) and ETo /CS

Summary

Introduction

Wheat is the main cereal crop belonging to the Poaceae family, which contributes 30%and 50% to the world grain production and grain trade, respectively [1]. Its quality and yield are directly associated with countrywide food security [2]. Wheat plants often suffer heat stress, which affects their quality and utilization worldwide. China alone are expected to show a decrease in wheat yield by 8% and 3%, respectively, due to the rise in worldwide mean temperature by 1 ◦ C. The impact of high temperature on the growth of plants is due to the excess output of reactive oxygen species (ROS) that damage the photosynthetic apparatus of plants by decreasing the rate of photosynthetic electron transport, inactivating the pigment system (PS) II center, degrading pigments and proteins, and eventually decreasing the yield [3]. ROS produced in chloroplasts as a result of abiotic stress hinder the synthesis of D1 protein, a component of the PS II complex [4]

Objectives

Methods

Results

Discussion

Conclusion