Metabolomics Analysis Reveals the Salt-Tolerant Mechanism in Glycine soja

Salinity is one of the major environmental constraints limiting crop plant yields around the world. Therefore, understanding the salt-tolerant mechanism and improving crop salt tolerance are two of the most effective ways of sustaining crop production worldwide. The differences in metabolite profiles were analyzed between common wild soybean and salt-tolerant wild soybean in response to neutral-salt stress and alkali-salt stress to elucidate the salt-tolerant mechanism. The results showed salt-tolerant wild soybean grew better than common wild soybean under both treatments. Differential metabolites profiling showed that the levels of some carbohydrates and fatty acids were lower in common wild soybean than in salt-tolerant wild soybean under salt stress. These metabolites included lactose, ribose, lauric acid, palmitic acid, stearic acid, and linolenic acid. Amino acid accumulation was observed in the two wild soybeans under alkali-salt stress. These amino acids were valine, tyrosine, glutamic acid, leucine, and isoleucine. The content of most organic acids and proline increased in salt-tolerant wild soybean subjected to alkali-salt stress. These organic acids included mucic acid, glutaric acid, galactonic acid, and dehydroascorbic acid. The TCA cycle was enhanced in common wild soybean in response to both treatments, but was reduced in salt-tolerant wild soybean. This study demonstrated the salt-tolerant mechanism in common wild soybean may encourage the TCA cycle to generate more ATP. However salt-tolerant wild soybean may regulate amino acid and organic acid metabolism to generate more compatible solutes. These findings provide an important theoretical foundation for the protection, development, and utilization of wild soybean resources.