Jasmonic acid ameliorates alkaline stress by improving growth performance, ascorbate glutathione cycle and glyoxylase system in maize seedlings

Mudaser Ahmad Mir,Pravej Alam,Riffat John,Parvaiz Ahmad,Mohammed Nasser Alyemeni

doi:10.1038/s41598-018-21097-3

Abstract

Environmental pollution by alkaline salts, such as Na2CO3, is a permanent problem in agriculture. Here, we examined the putative role of jasmonic acid (JA) in improving Na2CO3-stress tolerance in maize seedlings. Pretreatment of maize seedlings with JA was found to significantly mitigate the toxic effects of excessive Na2CO3 on photosynthesis- and plant growth-related parameters. The JA-induced improved tolerance could be attributed to decreased Na uptake and Na2CO3-induced oxidative damage by lowering the accumulation of reactive oxygen species and malondialdehyde. JA counteracted the salt-induced increase in proline and glutathione content, and significantly improved ascorbic acid content and redox status. The major antioxidant enzyme activities were largely stimulated by JA pretreatment in maize plants exposed to excessive alkaline salts. Additionally, increased activities of glyoxalases I and II were correlated with reduced levels of methylglyoxal in JA-pretreated alkaline-stressed maize plants. These results indicated that modifying the endogenous Na+ and K+ contents by JA pretreatment improved alkaline tolerance in maize plants by inhibiting Na uptake and regulating the antioxidant and glyoxalase systems, thereby demonstrating the important role of JA in mitigating heavy metal toxicity. Our findings may be useful in the development of alkali stress tolerant crops by genetic engineering of JA biosynthesis.

Highlights

Agricultural soil contamination by alkaline salts has been recognized for the past few decades; exposure to alkalinity still continues and is worsening, principally in Asian countries[1]
Alkaline-induced oxidative stress, plant cells are well furnished with inherent antioxidant capability that is comprised of enzymatic components, such as superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), ascorbate peroxidase (APX), glutathione S-transferase (GST), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR), as well as non-enzymatic components, such as glutathione (GSH) and ascorbic acid (AsA)[11,12]
Supplementation of jasmonic acid (JA) to Na2CO3 fed seedlings resulted in improved DW, which demonstrated the positive effects of JA on alkaline stress

Summary

Introduction

Agricultural soil contamination by alkaline salts has been recognized for the past few decades; exposure to alkalinity still continues and is worsening, principally in Asian countries[1]. Higher levels of alkaline salts in plant growth medium reduce K+ content and enhance Na uptake and accumulation, causing an efflux of K+ ions and promoting K+ leakage from plant cells[6,7,8]. Available information regarding the precise roles of JA in its simultaneous regulation of ROS and detoxification of MG under alkaline stress in crop plants is limited, and warrants in-depth investigation to understand how antioxidant metabolism changes in crop plants in response to Na2CO3 induced-toxicity. Our goal was to investigate the effects of JA on growth and physio-biochemical processes in maize by considering the mechanisms related to (i) Na+ and K+ uptake and homeostasis, (ii) JA-induced alterations in growth performance and oxidative parameters, (iii) the role of JA in the modification of non-enzymatic and enzymatic defences, and (iv) MG detoxification under alkaline-stress conditions. The current study was undertaken to evaluate the effects of JA on growth, ion homeostasis, antioxidants, and methylglyoxal metabolizing enzyme activity in the amelioration of alkaline stress in maize plants

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Conclusion