Jasmonic Acid Modulates the Physio-Biochemical Attributes, Antioxidant Enzyme Activity, and Gene Expression in Glycine max under Nickel Toxicity.

Elsayed Fathi Abd-Allah,Mudaser Ahmad Mir,Geetika Sirhindi,Parvaiz Ahmad,Salih Gucel

doi:10.3389/fpls.2016.00591

Elsayed Fathi Abd-Allah, Mudaser Ahmad Mir + Show 3 more

Open Access

https://doi.org/10.3389/fpls.2016.00591

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Abstract

In present study, we evaluated the effects of Jasmonic acid (JA) on physio-biochemical attributes, antioxidant enzyme activity, and gene expression in soybean (Glycine max L.) plants subjected to nickel (Ni) stress. Ni stress decreases the shoot and root length and chlorophyll content by 37.23, 38.31, and 39.21%, respectively, over the control. However, application of JA was found to improve the chlorophyll content and length of shoot and root of Ni-fed seedlings. Plants supplemented with JA restores the chlorophyll fluorescence, which was disturbed by Ni stress. The present study demonstrated increase in proline, glycinebetaine, total protein, and total soluble sugar (TSS) by 33.09, 51.26, 22.58, and 49.15%, respectively, under Ni toxicity over the control. Addition of JA to Ni stressed plants further enhanced the above parameters. Ni stress increases hydrogen peroxide (H2O2) by 68.49%, lipid peroxidation (MDA) by 50.57% and NADPH oxidase by 50.92% over the control. Supplementation of JA minimizes the accumulation of H2O2, MDA, and NADPH oxidase, which helps in stabilization of biomolecules. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) increases by 40.04, 28.22, 48.53, and 56.79%, respectively, over the control in Ni treated seedlings and further enhancement in the antioxidant activity was observed by the application of JA. Ni treated soybean seedlings showed increase in expression of Fe-SOD by 77.62, CAT by 15.25, POD by 58.33, and APX by 80.58% over the control. Nevertheless, application of JA further enhanced the expression of the above genes in the present study. Our results signified that Ni stress caused negative impacts on soybean seedlings, but, co-application of JA facilitate the seedlings to combat the detrimental effects of Ni through enhanced osmolytes, activity of antioxidant enzymes and gene expression.

Highlights

Plants being sessile experience variety of biotic and abiotic stresses
Jasmonic acid (JA) treated and untreated seeds were grown in autoclaved petri dishes lined with Whatman filter paper placed in growth chamber under average day/night temperature of 25◦C/16◦C and with 80% relative humidity
The shoot length decreases by 37.23% with Ni treatment, plants treated with Ni in presence of JA showed increase in shoot length by 30.74% over control plants (Table 2)

Summary

Introduction

Metal toxicity is most prevalent factor for polluting the soil and water bodies globally (Ahmad et al, 2015b). Some metals are essential for the normal functioning of plant cell, few are noxious and hampers plant growth and development (Ahmad et al, 2012b, 2015b). Nickel (Ni) is one of the essential metal elements required in small amounts by the plants. Ni is considered to be highly toxic element as it enters the food chain and causes carcinogenesis (Kasprzak et al, 2003). Excess of metals in agricultural soils cause osmotic and ionic stress to many crop plants (Ahmad et al, 2015b). Ni toxicity hampers seed germination and plant growth in terms of shoot and root length (Yusuf et al, 2011). The root growth inhibition may be due to the obstruction in mitotic activity (Gajewska et al, 2006)

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