Exogenous Application of Methyl Jasmonate and Salicylic Acid Mitigates Drought-Induced Oxidative Damages in French Bean (Phaseolus vulgaris L.).

Dipa Talukder,Motiar Rohman,Tofazzal Islam,Mohammed Mohi-Ud-Din,Jalal Uddin Ahmed,Mirza Hasanuzzaman,S. V. Krishna Jagadish

doi:10.3390/plants10102066

Abstract

Drought stress impairs the normal growth and development of plants through various mechanisms including the induction of cellular oxidative stresses. The aim of this study was to evaluate the effect of the exogenous application of methyl jasmonate (MeJA) and salicylic acid (SA) on the growth, physiology, and antioxidant defense system of drought-stressed French bean plants. Application of MeJA (20 μM) or SA (2 mM) alone caused modest reductions in the harmful effects of drought. However, combined application substantially enhanced drought tolerance by improving the physiological activities and antioxidant defense system. The drought-induced generation of O2●− and H2O2, the MDA content, and the LOX activity were significantly lower in leaves when seeds or leaves were pre-treated with a combination of MeJA (10 μM) and SA (1 mM) than with either hormone alone. The combined application of MeJA and SA to drought-stressed plants also significantly increased the activities of the major antioxidant enzymes superoxide dismutase, catalase, peroxidase, glutathione peroxidase, and glutathione-S-transferase as well as the enzymes of the ascorbate–glutathione cycle. Taken together, our results suggest that seed or foliar application of a combination of MeJA and SA restore growth and normal physiological processes by triggering the antioxidant defense system in drought-stressed plants.

Highlights

French bean (Phaseolus vulgaris L.) is one of the world’s most widely cultivated bean species [1]
Our findings provide support for earlier results showing that French beans under drought stress have significantly lower Canopy temperature depression (CTD), Leaf relative water content (LRWC), and Cell membrane stability (CMS); these reductions were suppressed by the application of methyl jasmonate (MeJA) or salicylic acid (SA) and statistically significantly suppressed by the combined MeJA + SA treatment Figures 3 and S1B)
The enhanced CTD, LRWC, and CMS in the drought-stressed French bean plants treated with MeJA and SA in the present study indicates that these hormones, when supplied in combination, have the potential to reduce the harmful effects of drought by maintaining cellular water status and maintaining a cooler leaf temperature

Summary

Introduction

French bean (Phaseolus vulgaris L.) is one of the world’s most widely cultivated bean species [1]. In Central and South America it accounts for 90% of total bean production [2]. It is a dual-purpose crop that is grown as pulse (grain) and consumed in the immature stage as a tender vegetable [3]. 60% of the regions around the world is affected by drought stress during different periods of crop growth [1,4]. Drought stress decreases plant growth and development by changing plant morphology and triggering variations in a suite of key physiological and biochemical processes [5]. Drought stress during the bean flowering period decreases the number of pods per plant and the number of seeds per pod [7], thereby reducing productivity. Longer, and more severe droughts, accompanied by erratic rainfall, are expected in the 21st century across many regions of the world [8,9], including

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