Cold stress in soybean (Glycine max L.) roots: Exogenous gallic acid promotes water status and increases antioxidant activities

Ceyda Ozfidan-Konakci,Evren Yildiztugay,Aysegul Yildiztugay,Mustafa Kucukoduk

doi:10.2298/botserb1901059o

Ceyda Ozfidan-Konakci, Evren Yildiztugay + Show 2 more

Open Access

https://doi.org/10.2298/botserb1901059o

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Abstract

Gallic acid (GLA; 3,4,5- trihydroxybenzoic acid) is a strong antioxidant in plants. In order to clarify the effects of GLA as a pro-oxidant or an antioxidant on cells under stress conditions, soybean (Glycine max) was grown under normal conditions or in the presence of cold stress (5 and 10?C) in the absence or presence of gallic acid (GLA; 1 and 2 mM) for 72 h. The soybean roots exposed to stress exhibited a significant decline in growth (RGR), water content (RWC), osmotic potential (??) and proline content (Pro). However, GLA treatment under stress significantly improved these parameters and alleviated the stress-generated damage. Stress decreased superoxide dismutase (SOD) activity, but GLA effectively mitigated the adverse effects on enzyme activity. After stress treatment, only catalase (CAT) was induced in soybean roots, although it was not sufficient to prevent toxic hydrogen peroxide (H2O2) accumulation. Thus, the levels of lipid peroxidation (TBARS content) markedly increased. However, GLA contributed to detoxification of H2O2 and lipid peroxidation by enhancing activities of CAT and peroxidase (POX). In addition to these enzymes, SOD activity was able to scavenge superoxide anion radicals, as evidenced by decline in TBARS content. However, monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), total ascorbate (tAsA) and glutathione (GSH) showed a decline of content in roots treated with GLA (both concentrations) plus stress. Our results suggest a protective role of GLA, which may strengthen plant tolerance by ensuring efficient water use and enhancing antioxidant systems. In soybean roots, GLA successfully alleviated the toxicity of cold stress by modulating the activities of SOD, CAT and POX rather than enzymes of the ascorbate-glutathione cycle.

Highlights

Cold is one of the major abiotic stresses limiting the productivity, geographical distribution and yield of many important crops (Zhang et al 2009)
In the roots of soybean supplemented with gallic acid (GLA) under conditions of stress treatment, the increase in relative water content (RWC) was slight when compared to the stress treatment alone
The best improvement of RWC was at GLA1+10°C

Summary

Introduction

Cold is one of the major abiotic stresses limiting the productivity, geographical distribution and yield of many important crops (Zhang et al 2009). Phenolic compounds can play a role in germination, growth and development of plants at the cellular and molecular levels (Maqbool et al 2013) These compounds are efficient free radical scavengers and inhibitors of lipid peroxidation in the cell membrane (Michalak 2006). The antioxidant activity of phenolic compounds is mainly due to their redox properties, which can play an important role in adsorbing and neutralising free radicals, quenching singlet and triplet oxygen or decomposing peroxides. This feature has been attributed to the two or more phenolic hydroxyl groups in their chemical structure (Michalak 2006). The antioxidant ability of GLA provides protection against hydroxyl radical-induced deoxyribose degradation in the Fenton reaction (Kamdem et al 2012)

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