Integrated Physiological, Transcriptomic, and Metabolomic Analyses Revealed Molecular Mechanism for Salt Resistance in Soybean Roots.

Jie Jin,Yurong Bi,Xiaomin Wang,Keke Li,Jianfeng Wang,Xiaofan Na,Guohong Zhang,Shengwang Wang,Juan Qin

doi:10.3390/ijms222312848

Abstract

Salinity stress is a threat to yield in many crops, including soybean (Glycine max L.). In this study, three soybean cultivars (JD19, LH3, and LD2) with different salt resistance were used to analyze salt tolerance mechanisms using physiology, transcriptomic, metabolomic, and bioinformatic methods. Physiological studies showed that salt-tolerant cultivars JD19 and LH3 had less root growth inhibition, higher antioxidant enzyme activities, lower ROS accumulation, and lower Na+ and Cl- contents than salt-susceptible cultivar LD2 under 100 mM NaCl treatment. Comparative transcriptome analysis showed that compared with LD2, salt stress increased the expression of antioxidant metabolism, stress response metabolism, glycine, serine and threonine metabolism, auxin response protein, transcription, and translation-related genes in JD19 and LH3. The comparison of metabolite profiles indicated that amino acid metabolism and the TCA cycle were important metabolic pathways of soybean in response to salt stress. In the further validation analysis of the above two pathways, it was found that compared with LD2, JD19, and LH3 had higher nitrogen absorption and assimilation rate, more amino acid accumulation, and faster TCA cycle activity under salt stress, which helped them better adapt to salt stress. Taken together, this study provides valuable information for better understanding the molecular mechanism underlying salt tolerance of soybean and also proposes new ideas and methods for cultivating stress-tolerant soybean.

Highlights

The fresh weight and the dry weight in all cultivars were decreased under salt stress, JINDOU 19 (JD19) and LONGHUANG 3 (LH3) obviously lost less biomass than LONGDOU 2 (LD2) (Figure 1D,E)
These results suggested that JD19 and LH3 were more tolerant to salinity than LD2
The content of leucine showed a consistent decreasing trend in JD19 and LH3 but increased in LD2 (Figure 7A). These results indicated that the greater ability of amino acid metabolism regulation in JD19 and LH3 might be correlated with osmotic adjustment and energy metabolism coping with salinity stress

Summary

Introduction

Salt stress is a major restricting factor in agricultural production [1,2]. The salinized soil currently accounts for 8% of the world’s total land area, and it is expected that the area of irrigated agriculture and salt-affected farmland in semi-arid areas will double by. In order to meet the fast-growing food demand for the global population, it is estimated that food production needs to increase by 70–110% to maintain current levels by. It is crucial to enhance the salt tolerance of conventional crops without expanding agricultural land area [5]

Methods

Results

Discussion

Conclusion