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Soaking of soybean seeds is a prerequisite for the production of soy foods, and it has been shown that the extent of water absorbed during different imbibition conditions directly affects the quality of the subsequent soybean seed products by yet unknown mechanisms. In order to elucidate the molecular changes in soybean seeds during different soaking temperatures, we performed an integrated proteomics and metabolomics analysis of seeds soaked at 4, 25, and 55 °C. Proteomics analysis revealed that various enzymes related to carbohydrate and protein hydrolysis were activated in soybean seeds during water soaking at 55 °C. Interestingly, results obtained from this integrated proteomics and metabolomics study showed changes in various metabolites, including isoflavones, amino acids, and sugars, that were positively correlated with proteome changes occurring upon soaking at 55 °C. Furthermore, soaking of soybean seeds at 55 °C resulted in degradation of indigestible anti-nutrients such as raffinose oligosaccharides. Taken together, our results suggest that the seed soaking at a high temperature (55 °C) increases the nutritional value of soybean seeds by decreasing the contents of some of the common anti-nutrients.

BackgroundGinseng is one of the well-known medicinal plants, exhibiting diverse medicinal effects. Its roots possess anticancer and antiaging properties and are being used in the medical systems of East Asian countries. It is grown in low-light and low-temperature conditions, and its growth is strongly inhibited at temperatures above 25°C. However, the molecular responses of ginseng to heat stress are currently poorly understood, especially at the protein level.MethodsWe used a shotgun proteomics approach to investigate the effect of heat stress on ginseng leaves. We monitored their photosynthetic efficiency to confirm physiological responses to a high-temperature stress.ResultsThe results showed a reduction in photosynthetic efficiency on heat treatment (35°C) starting at 48 h. Label-free quantitative proteome analysis led to the identification of 3,332 proteins, of which 847 were differentially modulated in response to heat stress. The MapMan analysis showed that the proteins with increased abundance were mainly associated with antioxidant and translation-regulating activities, whereas the proteins related to the receptor and structural-binding activities exhibited decreased abundance. Several other proteins including chaperones, G-proteins, calcium-signaling proteins, transcription factors, and transfer/carrier proteins were specifically downregulated.ConclusionThese results increase our understanding of heat stress responses in the leaves of ginseng at the protein level, for the first time providing a resource for the scientific community.

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Korean ginseng is one of the most valuable medicinal plants worldwide. However, our understanding of ginseng proteomics is largely limited due to difficulties in the extraction and resolution of ginseng proteins because of the presence of natural contaminants such as polysaccharides, phenols, and glycosides. Here, we compared four different protein extraction methods, namely, TCA/acetone, TCA/acetone–MeOH/chloroform, phenol–TCA/acetone, and phenol–MeOH/chloroform methods. The TCA/acetone–MeOH/chloroform method displayed the highest extraction efficiency, and thus it was used for the comparative proteome profiling of leaf, root, shoot, and fruit by a label-free quantitative proteomics approach. This approach led to the identification of 2604 significantly modulated proteins among four tissues. We could pinpoint differential pathways and proteins associated with ginsenoside biosynthesis, including the methylerythritol 4–phosphate (MEP) pathway, the mevalonate (MVA) pathway, UDP-glycosyltransferases (UGTs), and oxidoreductases (CYP450s). The current study reports an efficient and reproducible method for the isolation of proteins from a wide range of ginseng tissues and provides a detailed organ-based proteome map and a more comprehensive view of enzymatic alterations in ginsenoside biosynthesis.