Changes in the Metabolome of Two Soybean Genotypes under Drought Stress

Abstract

Soybean is the world’s leading economic oilseed crop. Drought stress is a major constraint on the growth and yield stability of soybean. Here, wild soybean (Glycine soja Siebold & Zucc.) was found to be more drought tolerant than cultivated soybean (Glycine max (L.) Merr.) owing to morphological changes at the whole-plant level when subjected to 5% PEG-6000 treatment. Additionally, differential metabolites between two soybean genotypes seedlings leaves were analyzed at the cellular level using a gas chromatography-mass spectrometry-based metabolomics method. The root lengths of wild soybean increased and a high root/shoot ratio was maintained under drought stress conditions. In addition, the drought tolerance of wild soybean resulted from significantly greater levels of favorable metabolites, such as aromatic and serine family amino acids, as well as sugar and polylols involved in mannose and galactose metabolism, favorable secondary metabolites, and organic and fatty acids compared with cultivated soybean. At the same time, wild soybeans could maintain a stable TCA cycle and significantly enhance glycolysis to produce more energy and enhance the phosphate pentose pathway to create more reducing power. Our experimental results provide an important reference for the breeding of wild soybeans in arid environments, as well as methodological for utilizing wild soybeans and improving cultivated soybeans.