Enhancing Salt Tolerance in Soybean by Exogenous Boron: Intrinsic Study of the Ascorbate-Glutathione and Glyoxalase Pathways.

Hassan S Al-Zahrani,Hesham F Alharby,Khalid Rehman Hakeem,Mirza Hasanuzzaman,Kamrun Nahar

doi:10.3390/plants10102085

Hassan S Al-Zahrani, Hesham F Alharby + Show 3 more

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https://doi.org/10.3390/plants10102085

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Abstract

Boron (B) performs physiological functions in higher plants as an essential micronutrient, but its protective role in salt stress is poorly understood. Soybean (Glycine max L.) is planted widely throughout the world, and salinity has adverse effects on its physiology. Here, the role of B (1 mM boric acid) in salt stress was studied by subjecting soybean plants to two levels of salt stress: mild (75 mM NaCl) and severe (150 mM NaCl). Exogenous B relieved oxidative stress by enhancing antioxidant defense system components, such as ascorbate (AsA) levels, AsA/dehydroascorbate ratios, glutathione (GSH) levels, the GSH and glutathione disulfide ratios, and ascorbate peroxidase, monodehydroascorbate reductase, and dehydroascorbate reductase activities. B also enhanced the methylglyoxal detoxification process by upregulation of the components of the glyoxalase system in salt-stressed plants. Overall, B supplementation enhanced antioxidant defense and glyoxalase system components to alleviate oxidative stress and MG toxicity induced by salt stress. B also improved the physiology of salt-affected soybean plants.

Highlights

Soybean (Glycine max L.) is a widely grown legume in America, Asia, Europe, and Africa and is consumed mostly as oil and soy protein [1]
Plant height was reduced by 13% and 40% by exposure to mild and severe salt stress, respectively, compared to unstressed control plants
Leaf area decreased at both levels of salt stress, and B addition had no significant effect on the leaf area of the salt-treated plants (Figure 1B)

Summary

Introduction

Soybean (Glycine max L.) is a widely grown legume in America, Asia, Europe, and Africa and is consumed mostly as oil and soy protein [1]. Salt-affected soils are distinguished by the presence of considerable amounts of soluble salts that are taken up by the plants growing there. This salt accumulation results in plant water stress due to disrupted osmotic potential, as well as interrupted uptake of essential nutrients and disturbance of the plant ionic balance [3]. Biochemical and physiological changes due to salt stress inhibit germination and post-germination development, with decreased root and shoot growth as common consequences of salt stress. Different physiological processes, including transpiration, photosynthesis, and translocation of assimilates, are hindered under salinity [5]. Methylglyoxal generation can be increased 2- to 6-fold under abiotic stress [6]

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