Cai-qiong Yang

Partial improvements in the flavor quality of soybean seeds using intercropping systems with appropriate shading.

The profiles of isoflavone and fatty acids constitute important quality traits in soybean seeds, for making soy-based functional food products, due to their important contributions to the flavor and nutritional value of these products. In general, the composition of these constituents in raw soybeans is affected by cultivation factors, such as sunlight; however, the relationship of the isoflavone and fatty acid profiles with cultivation factors is not well understood. This study evaluated the isoflavone and fatty acid profiles in soybeans grown under a maize-soybean relay strip intercropping system with different row spacings, and with changes in the photosynthetic active radiation (PAR) transmittance. The effects of PAR on the isoflavone and fatty acid contents were found to be quadratic. Appropriate intercropping shading may reduce the bitterness of soybeans caused by soy aglycone and could improve their fatty acid composition.

Fungal Diversity in Field Mold-Damaged Soybean Fruits and Pathogenicity Identification Based on High-Throughput rDNA Sequencing

Continuous rain and an abnormally wet climate during harvest can easily lead to soybean plants being damaged by field mold (FM), which can reduce seed yield and quality. However, to date, the underlying pathogen and its resistance mechanism have remained unclear. The objective of the present study was to investigate the fungal diversity of various soybean varieties and to identify and confirm the FM pathogenic fungi. A total of 62,382 fungal ITS1 sequences clustered into 164 operational taxonomic units (OTUs) with 97% sequence similarity; 69 taxa were recovered from the samples by internal transcribed spacer (ITS) region sequencing. The fungal community compositions differed among the tested soybeans, with 42 OTUs being amplified from all varieties. The quadratic relationships between fungal diversity and organ-specific mildew indexes were analyzed, confirming that mildew on soybean pods can mitigate FM damage to the seeds. In addition, four potentially pathogenic fungi were isolated from FM-damaged soybean fruits; morphological and molecular identification confirmed these fungi as Aspergillus flavus, A. niger, Fusarium moniliforme, and Penicillium chrysogenum. Further re-inoculation experiments demonstrated that F. moniliforme is dominant among these FM pathogenic fungi. These results lay the foundation for future studies on mitigating or preventing FM damage to soybean.

Targeted metabolomics analysis of fatty acids in soybean seeds using GC-MS to reveal the metabolic manipulation of shading in the intercropping system

A field microenvironment varies with intercropping ecological planting patterns, especially its light conditions. Due to light reflection and absorption by maize leaves, spectral irradiance, red/far-red (R/FR) ratio, and photosynthetic active radiation (PAR) of the soybean canopy are decreased in a maize–soybean intercropping system as compared to those in sole cropping. In this study, a metabolomics method was applied to analyze fatty acid metabolism of soybeans grown under an intercrop shading condition. The results indicate that the fatty acid contents of the intercropped soybean were significantly higher than those of the sole-cropped soybeans. As the shading effect increased, the soybean fatty acids content showed a rise and fall tendency. Moreover, the partial least-squares discriminant analysis (PLS-DA), Pearson correlation, and hierarchical clustering analysis (HCA) multivariate analyses showed a similar result. The results suggested that shading can manipulate soybean fatty acid metabolism in a maize–soybean strip intercropping system. Further, the metabolite profiling combined with multivariate statistical analysis can be used as a useful tool for identifying the metabolic links between fatty acid metabolites.

Metabolomic tool to identify soybean [ Glycine max (L.) Merrill] germplasms with a high level of shade tolerance at the seedling stage

The isoflavone profiles of seeds of various soybean genotypes with different levels of shade tolerance at the seedling stage were investigated. High-performance liquid chromatography (HPLC) was used to quantify 12 isoflavones, and the data were analyzed using a multivariate statistical analysis. Combined with field experimental data and an orthogonal partial least-squares discriminant analysis (OPLS-DA), several aglycones (genistein (GE), daidzein (DE), and glycitein (GLE)) were selected and identified as key compounds involved in the shade tolerance of soybean seedlings. Additional correlation analysis and laboratory shading stress experiments with soybean seedlings also confirmed the function of these selected isoflavones, especially GE, in the discrimination of soybean seedlings with different levels of shade tolerance. Furthermore, the structure–antioxidant activity relationships between a range of isoflavones and the plant shade-tolerance mechanism are discussed. Targeted metabolomic analyses of isoflavones could reveal the diversity of shade tolerance in soybean seedlings, thus contributing to the breeding of excellent soybean varieties.

Metabolism variation and better storability of dark- versus light-coloured soybean (Glycine max L. Merr.) seeds

The effects of storage duration on the seed germination and metabolite profiling of soybean seeds with five different coloured coats were studied. Their germination, constituents and transcript expressions of isoflavones and free fatty acids (FFAs) were compared using chromatographic metabolomic profiling and transcriptome sequencing. The seed water content was characterized using nuclear magnetic resonance (NMR) relaxometry. Results showed that dark-coloured seeds were less inactivated than light-coloured seeds. The aglycone and β-glucoside concentrations of upstream constituents increased significantly, whereas the acetylglucosides and malonylglucosides of downstream constituents decreased with an increase in the storage period. FFAs increased considerably in the soybean seeds as a result of storage. These results indicate that dark-coloured soybean seeds have better storability than light-coloured seeds, and seed water content plays a role in seed inactivation. It was concluded that there are certain metabolic regularities that are associated with different coloured seed coats of soybeans under storage conditions.

Organ-Specific Differential NMR-Based Metabonomic Analysis of Soybean [Glycine max (L.) Merr.] Fruit Reveals the Metabolic Shifts and Potential Protection Mechanisms Involved in Field Mold Infection

Prolonged, continuous rainfall is the main climatic characteristic of autumn in Southwest China, and it has been found to cause mildew outbreaks in pre-harvest soybean fields. Low temperature and humidity (LTH) stress during soybean maturation in the field promotes pre-harvest mildew, resulting in damage to different organs of soybean fruits to different extents, but relatively little information on the resistance mechanisms in these fruits is available. Therefore, to understand the metabolic responses of soybean fruits to field mold (FM), the metabonomic variations induced by LTH were characterized using proton nuclear magnetic resonance spectroscopy (1H-NMR), and the primary metabolites from the pod, seed coat and cotyledon of pre-harvest soybean were quantified. Analysis of FM-damaged soybean germplasms with different degrees of resistance to FM showed that extracts were dominated by 66 primary metabolites, including amino acids, organic acids and sugars. Each tissue had a characteristic metabolic profile, indicating that the metabolism of proline in the cotyledon, lysine in the seed coat, and sulfur in the pod play important roles in FM resistance. The primary-secondary metabolism interface and its potential contribution to FM resistance was investigated by targeted analyses of secondary metabolites. Both the seed coat and the pod have distinct but nonexclusive metabolic responses to FM, and these are functionally integrated into FM resistance mechanisms.

Application of targeted 1H NMR profiling to assess the seed vitality of soybean [Glycine max (L.) Merr.]

The assessment of seed vitality is a common challenge for phytologists, especially with the small amount of precious germplasms involved in breeding research. Researchers try to avoid the loss of precious samples as much as possible. A simple, rapid, and convenient method is urgently required to assess seed longevity or vitality without large dosages and tedious procedures. Therefore, in this study, a comprehensive, simple, very rapid, and convenient method based on 1H NMR profiling was developed to quantify the constituents in soybean seeds. Additionally, the general and individual partial least-squares discriminant analysis (PLS-DA) approach was used to analyze the vitality determination of black and yellow soybean germplasms, and the corresponding loadings scatter plot and difference analysis helped to identify the biomarkers in soybean seeds with varied seed vitalities. The result demonstrates that arginine, hypoxanthine, O-phosphocholine, and tryptophan are important biomarkers to assess the seed vitality of soybean. The detection of these biomarkers provides an approach for the assessment of soybean seed vitality.

Metabolite profiling of isoflavones and anthocyanins in black soybean [Glycine max (L.) Merr.] seeds by HPLC-MS and geographical differentiation analysis in Southwest China

Metabolite profiling of isoflavones and anthocyanins in black soybean seeds (BSSs) collected from different geographical locations in Southwest China was performed. A more rapid and convenient method was established to identify and quantify twelve isoflavones and eight anthocyanins in BSSs by HPLC-MS analyses. The results indicated that β-glucoside (G-type) and malonylglucoside (M-type) derivatives, cyanidin-3-glucoside (CYL) and peonidin-3-glucoside (PEO) are the major compounds found predominantly in the isoflavones and anthocyanins of BSSs. Combined with geographical data and orthogonal partial least-squares discriminant analysis (OPLS-DA), it was demonstrated that higher isoflavone contents were found in the samples grown in the high-longitude areas of Guizhou and Chongqing, while higher anthocyanin contents were found in the samples grown in the high-latitude areas of Chongqing and Sichuan. Geographical location affected the accumulation of secondary metabolites involved in the phenylpropane pathway, especially in the trade-off/balance between isoflavone and anthocyanin biosynthesis in BSSs. Overall, a high-latitude environment has beneficial effects on the metabolism of the phenylpropane pathway, and a high-longitude environment can promote isoflavone biosynthesis, while a low-longitude environment is favorable for anthocyanin biosynthesis in BSSs.

Effects of Continuous Shade Stress during Procreation Growth Stage on Isoflavone and Lignin Accumulation in Developing Soybean Seed

a Key Laboratory of Crop Ecophysiology and Farming System in Southwest, Ministry of Agriculture, Chengdu 611130, China b Institute of Ecological Agriculture, Sichuan Agricultural University, Chengdu 611130, China * Corresponding author. Tel.: +28 86290960; fax: +28 86290870. E-mail address: jingzhang@sicau.edu.cn (J. Zhang), mssiyangwy@sicau.edu.cn (W.-Y. Yang). 1 These authors contributed equally to this work.

DA-6 promotes germination and seedling establishment from aged soybean seeds by mediating fatty acid metabolism and glycometabolism

The plant growth regulator diethyl aminoethyl hexanoate (DA-6) promotes the germination and seedling establishment of aged soybean seeds through enhancing the conversion from triacylglycerol to fatty acids and sugars.