Spatial differences in soybean bioactive components across China and their influence by weather factors

Occurrence and distribution of phytic acid and its degradation products in soybeans in China: Analytical challenges

Phytic acid (IP6) and its degradation products lower myo-inositol phosphates exert different impacts on nutrient bioavailability and product quality characteristics. However, information regarding the occurrence of IP6 and its degradation products is scarce. In this work, simultaneous determination of IP6 and its degradation products in soybeans was developed, with emphasis on analysis by UPLC-MS/MS and a BEH Amide column both with hybrid surface technology. The retention and analyte/metal surface interactions issues were effectively addressed without ion-pairing reagents addition or derivatization. This method was applied to analyze soybeans from China. Total contents were 0.44-13.2 mg/g, and IP6 and its degradation product myo-inositol pentakisphosphate (IP5) were the predominant analytes, accounting for over 99%. Accession type significantly affected IP5 content, and landraces had significantly higher IP5 than cultivars. Geographically, the lowest IP6 was concentrated in the Huanghuaihai region. Significant correlations existed between IP6 and longitude, altitude, and annual cumulative sunshine hours. This study provides comprehensive insights into the IP6 and its degradation product profile in soybeans, which will benefit breeding soybeans based on specific requirements.

Geographic distributions and the regionalization of soybean seed compositions across China

As one of major food crops, soybean is grown over a broad ecological region in China with considerable variations in environmental conditions, and the seed compositions of soybeans are diverse among different regions. To clarify the spatial patterns of soybean seed compositions, crude oil, protein, and 11 categories of functional components were quantified in 1792 soybean samples collected from a vast range of soybean planting regions across China spanning from 2010 to 2017. The Kriging interpolation maps presented a clear north-to-south (high latitude to low latitude) increasing trend in contents of crude protein and dietary fiber and decreasing trend in contents of crude oil, phospholipids, saponins, and carotenoids. Soybeans with high-level of total oligosaccharide were concentrated in the central region. Based on the geographical distribution of soybean nutritional components, weather conditions, and cultivation systems, the soybean production areas in China were divided into three regions and 10 subregions. This study highlights the geographic distribution of soybean nutritional compositions and provides scientific evidence for guiding the construction of high-quality edible soybean production bases in China.

Can Soybean Cultivars with Larger Seed Size Produce More Protein, Lipids, and Seed Yield? A Meta-Analysis

Increasing soybean production and ensuring greater access to soybean protein and lipids is critical for global food security and human health. Seed size (i.e., seed weight) is one of the most important agronomic traits of soybean, which not only determines the seed yield, but can also affect the yield of protein and lipids. In China, farmers favor soybean cultivars with large seeds, which they believe produce more protein and lipids; however, experimental evidence supporting this belief is lacking. Therefore, we conducted field experiments from 2017 to 2020 at 35 locations across the Huang-Huai-Hai region (HHH) of China with 64 soybean cultivars. The seed yield, seed protein content, and seed lipids content of soybean, and their relationship with seed size were investigated. The highest seed yield (i.e., seed weight per unit area) was 2996.5 kg ha−1 in the north of HHH. However, the highest seed protein content was found in the south of HHH (42.5%) for the higher temperature, which was significantly higher than that of the middle (41.7%) and north of HHH (40.2%). In contrast, the highest seed lipids content was 20.7% in the north of HHH. Temperature, which had a path coefficient on seed yield of 0.519, can promote soybean seed yield. The correlation analysis indicated that the selection of the large seed size cultivar did not increase seed yield, and even led to a reduction of seed yield under high-yield environmental conditions. The seed protein content of soybean was not increased in the cultivars with large seed sizes. In addition, under different levels of seed lipids content (<20.30% or >20.30%), a significantly negative relationship was found between seed lipids content and hundred seed weight. Therefore, it is recommended that farmers choose to plant cultivars with smaller soybean seed sizes, so as to ensure high and stable soybean seed yield and obtain more vegetable protein and lipids per unit area.

Identification of QTN-by-environment interactions and their candidate genes for soybean seed oil-related traits using 3VmrMLM

INTRODUCTION

Although seed oil content and its fatty acid compositions in soybean were affected by environment, QTN-by-environment (QEIs) and gene-by-environment interactions (GEIs) were rarely reported in genome-wide association studies.

METHODS

The 3VmrMLM method was used to associate the trait phenotypes, measured in five to seven environments, of 286 soybean accessions with 106,013 SNPs for detecting QTNs and QEIs.

RESULTS

Seven oil metabolism genes (GmSACPD-A, GmSACPD-B, GmbZIP123, GmSWEET39, GmFATB1A, GmDGAT2D, and GmDGAT1B) around 598 QTNs and one oil metabolism gene GmFATB2B around 54 QEIs were verified in previous studies; 76 candidate genes and 66 candidate GEIs were predicted to be associated with these traits, in which 5 genes around QEIs were verified in other species to participate in oil metabolism, and had differential expression across environments. These genes were found to be related to soybean seed oil content in haplotype analysis. In addition, most candidate GEIs were co-expressed with drought response genes in co-expression network, and three KEGG pathways which respond to drought were enriched under drought stress rather than control condition; six candidate genes were hub genes in the co-expression networks under drought stress.

DISCUSSION

The above results indicated that GEIs, together with drought response genes in co-expression network, may respond to drought, and play important roles in regulating seed oil-related traits together with oil metabolism genes. These results provide important information for genetic basis, molecular mechanisms, and soybean breeding for seed oil-related traits.

An updated review of functional properties, debittering methods, and applications of soybean functional peptides

Soybean functional peptides (SFPs) are obtained via the hydrolysis of soybean protein into polypeptides, oligopeptides, and a small amount of amino acids. They have nutritional value and a variety of functional properties, including regulating blood lipids, lowering blood pressure, anti-diabetes, anti-oxidant, preventing COVID-19, etc. SFPs have potential application prospects in food processing, functional food development, clinical medicine, infant milk powder, special medical formulations, among others. However, bitter peptides containing relatively more hydrophobic amino acids can be formed during the production of SFPs, seriously restricting the application of SFPs. High-quality confirmatory human trials are needed to determine effective doses, potential risks, and mechanisms of action, especially as dietary supplements and special medical formulations. Therefore, the physiological activities and potential risks of soybean polypeptides are summarized, and the existing debitterness technologies and their applicability are reviewed. The technical challenges and research areas to be addressed in optimizing debittering process parameters and improving the applicability of SFPs are discussed, including integrating various technologies to obtain higher quality functional peptides, which will facilitate further exploration of physiological mechanism, metabolic pathway, tolerance, bioavailability, and potential hazards of SFPs. This review can help promote the value of SFPs and the development of the soybean industry.

Seed isoflavone profiling of 1168 soybean accessions from major growing ecoregions in China

Soybean (Glycine max L. Merrill) isoflavones are secondary metabolites of great interest because of their beneficial impact on human health. We profiled the seed isoflavone composition of 1168 soybean accessions collected from diverse ecoregions of China in three locations over two years. We observed significant differences in isoflavone content among the accessions, accession types, years of growth and ecoregions of origin. Total isoflavone (TIF) concentration of the soybean accessions ranged from 745 μg g-1 to 5253.98 μg g-1, which represents a 7-fold difference. The highest mean TIF concentration (2689.27 μg g-1) was observed in the Huang Huai Hai Valley Region (HR) accessions, followed by accessions from the Southern Region (SR) and Northern Region (NR) with TIF concentration of 2518.91 μg g-1 and 1942.78 μg g-1, respectively. Thirty-five accessions were identified as elite soybean resources based on their higher TIF concentration (4024.74 μg g-1 to 5253.98 μg g-1). Pairwise correlation analysis showed significant positive correlations between individual isoflavones and TIF concentrations. Malonyldaidzin and malonylgenistin showed the highest correlations with TIF concentration (r = 0.90 and r = 0.92, respectively), whereas acetyldaidzin showed the lowest correlation. The main isoflavone components had significant negative correlations with latitude and longitude, indicating that the geographical origin of the accessions influenced their seed isoflavone composition. Based on principal component analysis, glycosides and malonylglycosides of isoflavones were the major discriminative components for the soybean accessions. The present study demonstrated the geographical distribution of soybean seed isoflavone concentrations across the main ecoregion of China. The identified soybean accessions with both high and low TIF concentrations, which are desirable materials for industrial uses and could also be used as parents to breed soybean lines with improved isoflavone quantity and composition in the seeds.

Phenolic Compound Profile and Functionality of Aqueous Overripe Tempe Extracts

Tempe is a soy fermentation product and has been associated with many health benefits. It is usually consumed after 48 hours of fermentation; however extended fermentation is sometimes favoured. Since cooking involves water, it is of interest to study the health benefits of tempe water extract. In this study, we focused our study on total phenols, total flavonoids, DPPH free radical scavenging activity, cytotoxic activity, and identification of the main flavonoids. Our findings demonstrated that concentration of water-soluble flavonoids in tempe increased as fermentation time was prolonged. Fermentation for 60 hr resulted in extracts with very noticeable cytotoxic activity against MCF-7 cancer cell line (IC50 of 8.70 µg/ml). The cytotoxic activity of the extracts was fermentation time-dependent following non-linear relationship. The activity showed strong inverse correlation with total phenols and flavonoids in the extracts. LC-MS/MS data suggested that extracts from control and 24-hr fermented tempe demonstrated the highest responses for genistein, genistin, daidzein, daidzin, and glycitein, compared to those of other treatments and therefore suggested that excessive amount of the isoflavones, particularly genistein, induced cancer cell proliferation but lesser yet optimum concentration (observed at 60 hr-fermentation) contributed to otherwise effect.