Soybean Protein Content Research Articles

Genetic architecture of protein and oil content in soybean seed and meal.

Soybean is grown primarily for the protein and oil extracted from its seed and its value is influenced by these components. The objective of this study was to map marker-trait associations (MTAs) for the concentration of seed protein, oil, and meal protein using the soybean nested association mapping (SoyNAM) population. The composition traits were evaluated on seed harvested from over 5000 inbred lines of the SoyNAM population grown in 10 field locations across 3 years. Estimated heritabilities were at least 0.85 for all three traits. The genotyping of lines with single nucleotide polymorphism markers resulted in the identification of 107 MTAs for the three traits. When MTAs for the three traits that mapped within 5cM intervals were binned together, the MTAs were mapped to 64 intervals on 19 of the 20 soybean chromosomes. The majority of the MTA effects were small and of the 107 MTAs, 37 were for protein content, 39 for meal protein, and 31 for oil content. For cases where a protein and oil MTAs mapped to the same interval, most (94%) significant effects were opposite for the two traits, consistent with the negative correlation between these traits. A coexpression analysis identified candidate genes linked to MTAs and 18 candidate genes were identified. The large number of small effect MTAs for the composition traits suggest that genomic prediction would be more effective in improving these traits than marker-assisted selection.

Soybean sorting based on protein content using X-ray fluorescence spectrometry

The purpose of this research was to evaluate performance of an energy-dispersive X-ray fluorescence (XRF) sensor to classify soybean based on protein content. The hypothesis was that sulfur signals and other XRF spectral features can be used as proxies to infer soybean protein content. Sample preparation and equipment settings to optimize detection of S and other specific emission lines were tested for this application. A logistic regression model for classifying soybean as high- or low-protein was developed based on XRF spectra and protein contents. Additionally, the model was validated with an independent set of samples. Global accuracies of the method were 0.83 (training set) and 0.81 (test set) and the corresponding kappa indices were 0.66 and 0.61, respectively. These numbers indicated satisfactory performance of the sensor, suggesting that XRF spectral features can be applied for screening protein content in soybean.

Influence of Water Deficit on the Chemical Composition of Soybean Grains

With relation to the present issue about the influence of the periodic water deficit on the content and yield of the main chemical components, summarized annual data have been used including years of different characteristics, with droughts in different vegetation phenophases of soybean: very dry, averagely dry and average. The experiment was conducted at the Agricultural University of Plovdiv. The experiment was set in 4 repetitions with a size of experimental plots - 30 m 2 , and the crop plots - 10 m 2 . Criteria for watering performance was pre-watering moisture of soil at option 5-80% under-soil moisture for the layer 0-60 cm. The irrigation norm for all options was 50 mm. The irrigation norm for option 5 was 150 mm, and for options 2, 3 and 4-100 mm. Irrigation was performed gravitative along short closed furrows. After the completion of all experimental options, there were established the content and yield of the main chemical components in soybean grains - raw fat content, raw protein, raw fibres, raw ash and non-nitrogen extracted substances. Watering cancellations in the period of seed filling decrease the raw protein content. Watering cancellation in the bean formation period has a negative influence on protein content in soybean or does not influence it at all. Watering cancellation during the reproductive period decreases raw protein yield, which leads to a decrease in grain yield. Regarding raw fats, the most favourable is the water cancellation in the period of seed filling which favours growth in their content. Watering cancellation in the period of seed filling leads to a more significant decrease in lysine content. Despite the watering cancellation in a particular phase, the application of the other two waterings increases carbohydrate content in soybean grains compared to that obtained in non-watering conditions.

Genetic dissection reveals the complex architecture of amino acid composition in soybean seeds.

Five loci related to soybean protein and amino acid contents were colocated by performing linkage mapping and GWAS. The haplotype analysis showed that Glyma.08G109100 may be useful to improve the soybean seed composition. Soybean (Glycine max (L.) Merr.) seeds are good protein sources. Although genetic variation is abundant, natural variation in seed amino acids and their derived traits is lacking across soybean accessions. Here, we determined the contents of protein and 17 amino acids, obtained 36 derived traits based on the protein and total amino acid contents, and derived 34 traits based on seven amino acid family groups. Furthermore, we performed a linkage analysis of the contents of 17 amino acids and 73 amino acid-derived traits based on the recombinant inbred line (RIL)-derived Kefeng No. 1 × Nannong 1138-2. Six hundred thirty-nine quantitative trait loci (QTLs) were identified, explaining 6.07-39.00% of the phenotypic variation. Among these loci, five were detected in diverse soybean accessions using a genome-wide association study. A network analysis revealed that some loci that were significantly associated with multiple amino acids were tightly linked on chromosome 8 based on linkage disequilibrium values, which also further confirmed the results of the correlation analysis among amino acid traits. Through a combination of a genome-wide association study, linkage analysis, qRT-PCR, and genomic polymorphism comparison, Glyma.08G109100 on chromosome 8, which may affect amino acid contents, was selected. The haplotype analysis showed that Hap-T of Glyma.08G109100 may be useful to improve the contents of protein and 16 amino acids in soybean. This study provides new insights into the genetic basis of the amino acid composition in soybean seeds and may facilitate marker-based breeding of soybean with improved nutritional value.

Effects of Liming on Nodulation, Nitrogen Fixation and Seed Protein Content in Soybean

Soil acidity is influenced by high levels of aluminium, iron, manganese and low levels of Cation Exchange Capacity (CEC), plant nutrients availability such as phosphorus, affect the growth of symbiotic-fixing bacteria in soybean which is detrimental to nodule formation and functioning. In an attempt to evaluate liming effects on soil pH, nitrogen fixation and seed protein content, an experiment was set up using a randomized complete block design (RCBD) layout in a split-plot with four replications at the Crop Museum, the Sokoine University of Agriculture in Morogoro, Tanzania. Soybean genotypes (Bossier, Laela and Uyole soya-1) were used as the main plot, while lime levels (1560, 936 and 624 kg/ha) were used as the subplot. The analysis of variance (ANOVA) showed a significant influence of lime levels on soil pH, quantities of nitrogen fixed and seed protein content. There was a significant difference (P = 0.001) observed among soybean genotypes with the application of 1560 kg/ha of lime (pH 6.5), recording the highest (7.6) nodule counts and nodule dry weight (19.26). Among the different varieties used in the study, Bossier was observed to have a fixed 24.46 kgN/ha, while Laela produced the highest (10.60%) seed protein content. Application of 1560 kg/lime observed a significant increase in kgN/ha (35.71) as well as a minimal increase (15.66%) in seed protein content at pH 6.5. Interaction effects (P = 0.05), however, observed Laela has fixed the highest nodule (7.6) counts, nitrogen fixation (44.90 kgN/ha), with Bossier recording the highest (20.22%) seed protein. The study revealed that the physiochemical properties of acid soil, as well as soybean yield components such as nodules, N2 fixation and seed protein content, can be maximally improved when limed with CaCo3

Pinpointing Genomic Regions and Candidate Genes Associated with Seed Oil and Protein Content in Soybean through an Integrative Transcriptomic and QTL Meta-Analysis.

Soybean with enriched nutrients has emerged as a prominent source of edible oil and protein. In the present study, a meta-analysis was performed by integrating quantitative trait loci (QTLs) information, region-specific association and transcriptomic analysis. Analysis of about a thousand QTLs previously identified in soybean helped to pinpoint 14 meta-QTLs for oil and 16 meta-QTLs for protein content. Similarly, region-specific association analysis using whole genome re-sequenced data was performed for the most promising meta-QTL on chromosomes 6 and 20. Only 94 out of 468 genes related to fatty acid and protein metabolic pathways identified within the meta-QTL region were found to be expressed in seeds. Allele mining and haplotyping of these selected genes were performed using whole genome resequencing data. Interestingly, a significant haplotypic association of some genes with oil and protein content was observed, for instance, in the case of FAD2-1B gene, an average seed oil content of 20.22% for haplotype 1 compared to 15.52% for haplotype 5 was observed. In addition, the mutation S86F in the FAD2-1B gene produces a destabilizing effect of (ΔΔG Stability) -0.31 kcal/mol. Transcriptomic analysis revealed the tissue-specific expression of candidate genes. Based on their higher expression in seed developmental stages, genes such as sugar transporter, fatty acid desaturase (FAD), lipid transporter, major facilitator protein and amino acid transporter can be targeted for functional validation. The approach and information generated in the present study will be helpful in the map-based cloning of regulatory genes, as well as for marker-assisted breeding in soybean.

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.

Genetic variation and marker-trait association affect the genomic selection prediction accuracy of soybean protein and oil content.

Genomic selection (GS) is a potential breeding approach for soybean improvement. In this study, GS was performed on soybean protein and oil content using the Ridge Regression Best Linear Unbiased Predictor (RR-BLUP) based on 1,007 soybean accessions. The SoySNP50K SNP dataset of the accessions was obtained from the USDA-ARS, Beltsville, MD lab, and the protein and oil content of the accessions were obtained from GRIN. Our results showed that the prediction accuracy of oil content was higher than that of protein content. When the training population size was 100, the prediction accuracies for protein content and oil content were 0.60 and 0.79, respectively. The prediction accuracy increased with the size of the training population. Training populations with similar phenotype or with close genetic relationships to the prediction population exhibited better prediction accuracy. A greatest prediction accuracy for both protein and oil content was observed when approximately 3,000 markers with -log10(P) greater than 1 were included. This information will help improve GS efficiency and facilitate the application of GS.

Identification of loci governing soybean seed protein content via genome-wide association study and selective signature analyses.

Soybean [Glycine max (L.) Merr.] is an excellent source of protein. Understanding the genetic basis of protein content (PC) will accelerate breeding efforts to increase soybean quality. In the present study, a genome-wide association study (GWAS) was applied to detect quantitative trait loci (QTL) for PC in soybean using 264 re-sequenced soybean accessions and a high-quality single nucleotide polymorphism (SNP) map. Eleven QTL were identified as associated with PC. The QTL qPC-14 was detected by GWAS in both environments and was shown to have undergone strong selection during soybean improvement. Fifteen candidate genes were identified in qPC-14, and three candidate genes showed differential expression between a high-PC and a low-PC variety during the seed development stage. The QTL identified here will be of significant use in molecular breeding efforts, and the candidate genes will play essential roles in exploring the mechanisms of protein biosynthesis.

Yield trade‐off and the role of parental selection based on seed size when breeding for soybean seed protein

AbstractAlternative physiological strategies can increase protein concentration in soybean: (i) more‐than‐proportional increases in seed protein content (mg seed−1) relative to increases in carbohydrate and oil content in large‐seeded genotypes or (ii) more‐than‐proportional reductions in carbohydrate and/or oil content relative to protein content reductions in small‐seeded genotypes. Because these strategies differentially affect crop growth and development, we hypothesized that populations developed from high‐protein (HP) parents with contrasting seed sizes will present differences in how seed yield and protein concentration correlate. To test this, three breeding strategies were developed by mating high‐yielding cultivars and HP ones that differ in seed sizes, reflecting the alternative strategies mentioned above. Neither tested crossing strategies showed differences in their correlation values between seed yield and protein concentration, as initially expected. Nevertheless, populations developed from crossing a HP‐small‐seeded parent to a HP‐large‐seeded one showed the highest number of transgressive segregants for protein yield. Our results showed that parent selection based on seed size has no beneficial effects on the development of high‐yielding, HP soybean populations, but it might affect the number of transgressive segregants for protein yield.

Soybean Protein and Oil Variants Identified through a Forward Genetic Screen for Seed Composition.

Mutagenesis remains an important tool in soybean biology. In classical plant mutation breeding, mutagenesis has been a trusted approach for decades, creating stable non-transgenic variation, and many mutations have been incorporated into germplasm for several crops, especially to introduce favorable seed composition traits. We performed a genetic screen for aberrant oil or protein composition of soybean seeds, and as a result isolated over 100 mutant lines for seed composition phenotypes, with particular interest in high protein or high oil phenotypes. These lines were followed for multiple seasons and generations to select the most stable traits for further characterization. Through backcrossing and outcrossing experiments, we determined that a subset of the lines showed recessive inheritance, while others showed a dominant inheritance pattern that suggests the involvement of multiple loci and genetic mechanisms. These lines can be used as a resource for future studies of the genetic control of seed protein and oil content in soybean.

Cover crops affect soybean yield components, but not grain quality

AbstractCover cropping is mainly used to prevent soil erosion, but the effects of individual cover crops on the subsequent soybean [Glycine max (L.) Merr.] are hardly known. Therefore, two annual field trials with 15 cover crop species and bare fallow as control were conducted in semi‐arid East Austria in 2016 and 2017. Cover crops were sown in July in 3‐ × 10‐m plots in a randomized block design with three replicates and were incorporated in mid‐April before soybean were seeded. Cover crop biomass differed between plant species and year (2016, 626 ± 390; 2017, 84 ± 86.1 g m−2). Aboveground cover crop biomass did not affect soybean establishment, but single cover crop species such as ryegrass (Lolium multiflorum Lam. var. westerwoldicum Wittm.), kidney vetch (Anthyllis vulneraria L.), and corn cockle (Agrostemma githago L.) impeded soybean seeding due to high root densities and prevented germination or fostered outbreak of two‐spotted spider mites (Tetranychus urticae Koch). These three cover crops reduced soybean grain yield by 12–84%. Grain yield was a function of grain density m−2 in a three‐way interaction with year and cover crop treatment, but not by plant or pod density. Protein, oil, and sucrose content of soybean were unaffected by cover crop treatments. Overall, with the exception of ryegrass, kidney vetch, and corn cockle, cover crops can be grown ahead of soybean without any yield loss and can be used for their versatile ecosystem services.

Long-Term Corn–Soybean Rotation and Soil Fertilization: Impacts on Yield and Agronomic Traits

Although crop rotations have been widely shown as an effective approach for improving yield or soil quality in the long term, the relationship between crop rotations and quality traits of crop or biochar-based fertilization is still unclear. To address this, we conducted a long-term field experiment in the Heilongjiang province of China to investigate the effects of crop rotation and biochar-based fertilizer application on the crop yield, soil parameters, crop quality, and agronomic traits in 2014–2020. The effects of rotations on crop production and soil properties were evaluated with the average yield variability during the 7 years of this study. Our results showed that the diversified corn and soybean rotations had a significant positive effect on average crop yield compared with their monocultures. The corn yield was enhanced by 0.6 Mg ha−1 (5.4%) in the corn–soybean–corn (CSC) crop sequence compared with monoculture corn. Similarly, soybean yield was enhanced by 0.21 Mg ha−1 (9.7%) in the soybean–corn–corn (SCC) crop sequence compared with monoculture soybean. However, a negative effect of crop rotations was detected on the protein content of soybean compared with the monoculture soybean, while a positive effect was detected on oil content. Additionally, no differences were detected in crop yield between biochar-based fertilization and mineral fertilization treatments, but a significant positive effect of biochar-based fertilization was observed for any crop on both protein and oil content. A significant effect of crop rotation was found on the percentage of total soil N (TN), available soil N (AN), and available soil K (AK) content. The SSS crop sequence treatment illustrated the highest TN values at 0.18%. The CCC crop sequence treatment increased AN and AK content by 9.1% and 7.8%, respectively, compared with SSS (p &lt; 0.05). We conclude that crop rotations increase crop yield and biochar-based fertilizer application, improving crop quality traits in the long term. Thus, the addition of biochar-based fertilizer could efficiently enhance the yield and quality of crop in the rotation cropping system. The findings of this study may provide useful information for designing sustainable cropping systems based on rotations.

RNAi and CRISPR-Cas silencing E3-RING ubiquitin ligase AIP2 enhances soybean seed protein content.

The majority of plant protein in the world's food supply is derived from soybean (Glycine max). Soybean is a key protein source for global animal feed and is incorporated into plant-based foods for people, including meat alternatives. Soybean protein content is genetically variable and is usually inversely related to seed oil content. ABI3-interacting protein 2 (AIP2) is an E3-RING ubiquitin ligase that targets the seed-specific transcription factor ABI3. Silencing both soybean AIP2 genes (AIP2a and AIP2b) by RNAi enhanced seed protein content by up to seven percentage points, with no significant decrease in seed oil content. The protein content enhancement did not alter the composition of the seed storage proteins. Inactivation of either AIP2a or AIP2b by a CRISPR-Cas9-mediated mutation increased seed protein content, and this effect was greater when both genes were inactivated. Transactivation assays in transfected soybean hypocotyl protoplasts indicated that ABI3 changes the expression of glycinin, conglycinin, 2S albumin, and oleosin genes, indicating that AIP2 depletion increased seed protein content by regulating activity of the ABI3 transcription factor protein. These results provide an example of a gene-editing prototype directed to improve global food security and protein availability in soybean that may also be applicable to other protein-source crops.

Lactobacillus acidophilus and Lactobacillus cereus-containing products do reduce soybean antinutritional factors

Abstract. Soybean has shown over the years to be a reliable plant protein source to excellently substitute the high cost fishmeal in aquaculture diets. However, antinutritional factors (ANFs) limit its usage in aquaculture feeds. Therefore, the current study was designed to test the efficacy of three substrates containing different microorganisms that are capable of reducing soybean ANFs in a 3-month period at a low pH of 2.8. Full fat soybean (USB) was fermented using Anaerobic waste extract from Recirculating Aquaculture System sludge trap (RASW); Biocentric® Feed probiotic powder (BIOP); Oakland® double cream yoghurt (3x 106 CFU ml¯¹) (OY), Control treatment which had no substrate that contained fermenting microorganism (SRR). Each treatment was conducted in three replicates at 2.8 pH. The untreated soybean granules recorded a numerical protein content of 48.56%. The BIOP fermented soybean recorded significantly higher protein content as compared to the other soybean meal fermented with the other substrates. There was also a significant decrease in the soybean content of the amino acid lysine upon fermentation with the four treatments. Fermentation of the soybean with the four treatments was not significantly different in relation with their soybean lipid content, crude fibre content, methionine + cysteine, dry matter content, urease activity and gross energy content (P &gt; 0.05). There was an overall significant decrease in the ANFs when soybean was fermented with the four treatments, with four out of six analysed ANFs parameters content showing a significant decrease upon fermentation (P &lt; 0.05). Fermentation of the soybean with RASW resulted in a significant decrease of trypsin inhibitor content as compared to the rest of the treatments. The USB recorded a numerical value of 43.80 for trypsin inhibitor, whereas RASW fermented soybean recorded least trypsin inhibitor of 3815 ± 010 mg/g. In conclusion, the current study showed that the fermentation substrates used are capable of reducing soybean ANFs, with a slight decrease in soybean protein content.

Nitrogen fertilizer effects on soybean physiology, yield components, seed yield and protein content in the Southeastern United States

Soybean physiology, seed yield and composition can vary greatly and are a function of genetics, environment, and management practices. N fertilizer is not often applied to soybeans, but it can affect yield and seed composition, and the outcome of N fertilization has varied widely among studies. To test if certain physiological responses might be linked with positive agronomic responses to N fertilizer, a field study was conducted in varied environments unique to the Southeast United States (US). Five genotypes from maturity groups V-VII were evaluated. Although the environment and genotype had significant effects on most of the physiological characteristics and yield components measured, nitrogen application interacted significantly with environment for seed protein concentration, seed oil concentration, yield, and percent of nitrogen derived from the atmosphere in leaves during the seed fill period. The direction of the nitrogen effect on protein concentration differed among environments, increasing protein concentration in one environment and reducing protein concentration in another environment. Nitrogen application effects did not vary among the genotypes included in this study. Photosynthetic and nitrogen fixation responses to nitrogen application were not clearly linked with seed protein concentration response. A tailored nitrogen recommendation for environment is the best option for improving seed protein in this region with diverse environmental conditions.

Identification of Candidate Genes and Genomic Selection for Seed Protein in Soybean Breeding Pipeline.

Soybean is a primary meal protein for human consumption, poultry, and livestock feed. In this study, quantitative trait locus (QTL) controlling protein content was explored via genome-wide association studies (GWAS) and linkage mapping approaches based on 284 soybean accessions and 180 recombinant inbred lines (RILs), respectively, which were evaluated for protein content for 4 years. A total of 22 single nucleotide polymorphisms (SNPs) associated with protein content were detected using mixed linear model (MLM) and general linear model (GLM) methods in Tassel and 5 QTLs using Bayesian interval mapping (IM), single-trait multiple interval mapping (SMIM), single-trait composite interval mapping maximum likelihood estimation (SMLE), and single marker regression (SMR) models in Q-Gene and IciMapping. Major QTLs were detected on chromosomes 6 and 20 in both populations. The new QTL genomic region on chromosome 6 (Chr6_18844283–19315351) included 7 candidate genes and the Hap.XAA at the Chr6_19172961 position was associated with high protein content. Genomic selection (GS) of protein content was performed using Bayesian Lasso (BL) and ridge regression best linear unbiased prediction (rrBULP) based on all the SNPs and the SNPs significantly associated with protein content resulted from GWAS. The results showed that BL and rrBLUP performed similarly; GS accuracy was dependent on the SNP set and training population size. GS efficiency was higher for the SNPs derived from GWAS than random SNPs and reached a plateau when the number of markers was >2,000. The SNP markers identified in this study and other information were essential in establishing an efficient marker-assisted selection (MAS) and GS pipelines for improving soybean protein content.

Clustering of Fifth Generation Mutants of Genetically - Improved Kipas Putih Soybean with High Protein Content

Kipas Putih is one of the local varieties of soybean from Aceh, Indonesia. To improve the productivity of this variety, the irradiation mutation technique was applied. This study aimed to examine the level of genetic diversity in the M5 generation of Kipas Putih soybean using SSR markers and to identify whether any used markers were associated with the loci that control the protein content in soybean. A total of 18 SSR markers were used to amplify the DNA of 11 mutant lines of Kipas Putih. The total alleles detected were 55 alleles which range from 1 to 7 alleles per locus. The average of major allele’s frequency was 0.71 with the heterogeneity of 0.17. The PIC value ranged from 0.00 to 0.73 with an average of 0.35. Satt308 was identified as the most polymorphic marker among others since it had a PIC value greater than 0.70. The genetic distance analysis showed that the mutant lines B4, B10 and B13 had the furthest genetic distance (0.45) with the Kipas Putih (B0) soybean variety. The phylogenetic analysis showed Kipas Putih soybean and ten mutants of M5 generation grouped into four main clusters at a similarity coefficient of 0.20. Furthermore, association analysis showed that only two SSR markers, Satt577 and Satt431 were significantly associated with protein content with an R2 value of 0.7855 to 0.9643.

Stability of Protein and Oil Content in Soybean across Dry and Normal Environments—A Case Study in Croatia

Soybean is generally grown as a rainfed crop worldwide and very often is exposed to drought and high temperatures. The objectives of this study were to determine the performance and stability of 32 elite soybean genotypes for seed protein and oil contents across six dry and eight normal environments and to determine the influence of environment on the relationship between the two traits. In the combined ANOVA, genotypes (G), environments (E) and G × E were significant for both traits with protein content being more sensitive to environmental changes than oil content. Mean seed protein content decreased by 4.5% under drought conditions compared to normal ones and ranged from 2.3% to 7.1% for individual genotypes. At the same time drought caused a slight increase in seed oil content of +1.2%, with a range of −1.3% to +4.5% for individual genotypes. Genotype stability in terms of regression coefficient (b) and coefficient of variation (CV) was in moderate to weak negative correlation with mean genotype performance for protein content, while no correlation was observed between genotype stability and mean genotype performance for oil content. Protein and oil content were significantly negatively correlated in normal environments (r = −0.33), while no correlation between the traits was observed in dry environments (r = −0.02).

Preparation, structure and properties of soy protein and silk fibroin composite nanofiber membrane by jet spinning

<p indent=0mm>It is a hot topic in science nowadays and of great practical significance for developing abundant green natural resources and their applications in the research of biomedicine and tissue engineering. This article successfully prepared the biocompatible and biodegradable soy protein and silk fibroin composite nanofiber membrane by spinning technique. The apparent morphologies, structural changes and interactions of the two materials were characterized by scanning electron microscopy, Raman and Fourier transform infrared spectroscopy and X-ray diffraction. Differential scanning calorimetry and thermogravimetric analysis were used to investigate the blending properties of the two phases. The water retention, <italic>in vitro</italic> degradation, and cytocompatibility of the composite films were also evaluated. The results showed mainly hydrogen bond interactions between silk fibroin and soy protein molecular chains, which had thermodynamic compatibility and showed good morphology and thermal properties of nanofibers. With the increase of soybean protein content, the <italic>β</italic>-sheet content of the composite nanofiber membrane increases gradually. At the same time, the glass transition temperature decreases, the specific heat capacity increases a little more, and the water retention ability increases as well as the enzymatic degradation speed. Simultaneously, compared with pure silk fibroin, soy protein/silk fibroin composite nanofiber membrane can provide a better environment for cell adhesion and proliferation, which can be used as a wound dressing and drug delivery system. Especially, the composite fiber membrane containing 60% soy protein showed the strongest cell activity. This study provides a new view for preparing natural materials such as silk fibroin and soy protein and supplies the experimental and theoretical basis for the wide applications of green natural resources.