Acceptability of green soybeans as a vegetable entity

Genetic and Phenotypic Characterization of Soybean Landraces Collected from the Zhejiang Province in China

The soybean is an important feed, industrial raw material, and food crop in the world due to its rich components. There is a long history of soybean cultivation with different types and rich resources in the Zhejiang province of China. It is important to understand genetic diversity as well as phenotypic variation for soybean breeding. The objective of this study was to analyze both genetic and phenotypic characteristics of the 78 soybean landraces collected, and to explore a potential advantage of germplasm resources for further application. These 78 autumn-type soybean landraces have been propagated, identified, and evaluated in both 2021 and 2022. There were agronomic, quality, and genetic variations according to the comprehensive analyses. There was a good consistency between seed size and seed coat color. There were significant differences of seed protein, fat, and sugar contents based upon the seed coat color. These soybean landraces were genotyped using 42 simple sequence repeat markers and then clustered into two groups. The two groups had a consistency with the seed coat color. This study gave us a combined understanding of both the phenotypic variation and the genetic diversity of the soybean landraces. Therefore, the reasonable crossing between different soybean types is highly recommended.

Using transcriptomic and metabolomic data to investigate the molecular mechanisms that determine protein and oil contents during seed development in soybean

Soybean [Glycine max (L.) Merri.] is one of the most valuable global crops. And vegetable soybean, as a special type of soybean, provides rich nutrition in people's life. In order to investigate the gene expression networks and molecular regulatory mechanisms that regulate soybean seed oil and protein contents during seed development, we performed transcriptomic and metabolomic analyses of soybean seeds during development in two soybean varieties that differ in protein and oil contents. We identified a total of 41,036 genes and 392 metabolites, of which 12,712 DEGs and 315 DAMs were identified. Analysis of KEGG enrichment demonstrated that DEGs were primarily enriched in phenylpropanoid biosynthesis, glycerolipid metabolism, carbon metabolism, plant hormone signal transduction, linoleic acid metabolism, and the biosynthesis of amino acids and secondary metabolites. K-means analysis divided the DEGs into 12 distinct clusters. We identified candidate gene sets that regulate the biosynthesis of protein and oil in soybean seeds, and present potential regulatory patterns that high seed-protein varieties may be more sensitive to desiccation, show earlier photomorphogenesis and delayed leaf senescence, and thus accumulate higher protein contents than high-oil varieties.

Descriptive Analysis of Seven Leguminous Plants in Korea

Legumes are dicotyledonous plants, and they represent the third-largest plant family seeds distributed glo-bally. This study aimed to develop a lexicon for seven well-known legumes: kidney bean, mung bean, chickpea, green kernel black bean, black bean, soybean, and red bean. A sensory lexicon describing the aroma characteristics of legumes was developed, and the intensity of each aroma attribute was evaluated using a 15-point universal scale in Spectrum^TM. Nine aroma terms were developed: boiled egg yolk, bean sprout, chicken breast, boiled chestnut, soymilk, green bean, raw peanut shell, soil odor, and mango. The lexicon identified nine descriptions for the sensory characteristics of legumes. Kidney bean, mung bean, and red bean had high green bean, bean sprout, and soil odor aromas, whereas soybean, green kernel black bean, black bean, and chickpea had strong boiled egg yolk, boiled chestnut, and chicken breast aromas. These results can aid food product developers with flavor optimization in product formulation.

Genome sequencing and population resequencing provide insights into the genetic basis of domestication and diversity of vegetable soybean

Vegetable soybean is one of the most important vegetables in China, and the demand for this vegetable has markedly increased worldwide over the past two decades. Here, we present a high-quality de novo genome assembly of the vegetable soybean cultivar Zhenong 6 (ZN6), which is one of the most popular cultivars in China. The 20 pseudochromosomes cover 94.57% of the total 1.01 Gb assembly size, with contig N50 of 3.84 Mb and scaffold N50 of 48.41 Mb. A total of 55 517 protein-coding genes were annotated. Approximately 54.85% of the assembled genome was annotated as repetitive sequences, with the most abundant long terminal repeat transposable elements. Comparative genomic and phylogenetic analyses with grain soybean Williams 82, six other Fabaceae species and Arabidopsis thaliana genomes highlight the difference of ZN6 with other species. Furthermore, we resequenced 60 vegetable soybean accessions. Alongside 103 previously resequenced wild soybean and 155 previously resequenced grain soybean accessions, we performed analyses of population structure and selective sweep of vegetable, grain, and wild soybean. They were clearly divided into three clades. We found 1112 and 1047 genes under selection in the vegetable soybean and grain soybean populations compared with the wild soybean population, respectively. Among them, we identified 134 selected genes shared between vegetable soybean and grain soybean populations. Additionally, we report four sucrose synthase genes, one sucrose-phosphate synthase gene, and four sugar transport genes as candidate genes related to important traits such as seed sweetness and seed size in vegetable soybean. This study provides essential genomic resources to promote evolutionary and functional genomics studies and genomically informed breeding for vegetable soybean.

Genome-Wide Variation Analysis of Four Vegetable Soybean Cultivars Based on Re-Sequencing

Vegetable soybean is a type of value-added specialty soybean, served as a fresh vegetable or snack in China. Due to the difference from other types, it is important to understand the genetic structure and diversity of vegetable soybean for further utilization in breeding programs. The four vegetable cultivars, Taiwan-75, Zhexiandou No. 8, Zhexian No. 9 and Zhexian No. 10 are popular soybean varieties planted in Zhejiang province, and have large pods and intermediate maturity. The clustering showed a close relationship of these four cultivars in simple sequence repeat analysis. To reveal the genome variation of vegetable soybean, these four improved lines were analyzed by whole-genome re-sequencing. The average sequencing depth was 7X and the coverage ratio of each cultivar was at least more than 94%. Compared with the reference genome, a large number of single-nucleotide polymorphisms, insertion/deletions and structure variations were identified with different chromosome distributions. The average heterozygosity rate of the single-nucleotide polymorphisms was 11.99% of these four cultivars. According to the enrichment analysis, there were 23,371 genes identified with putative modifications, and a total of 282 genes were related to carbohydrate metabolic processes. These results provide useful information for genetic research and future breeding, which can facilitate the selection procedures in vegetable soybean breeding.

Genome-wide association analysis for yield-related traits at the R6 stage in a Chinese soybean mini core collection

BACKGROUND

Soybean (Glycine max (L.) Merr.) is an economically important crop for vegetable oil and protein production, and yield is a critical trait for grain/vegetable uses of soybean. However, our knowledge of the genes controlling the vegetable soybean yield remains limited.

OBJECTIVE

To better understand the genetic basis of the vegetable soybean yield.

METHODS

The 100-pod fresh weight (PFW), 100-seed fresh weight (SFW), kernel percent (KP) and moisture content of fresh seeds (MCFS) at the R6 stage are four yield-related traits for vegetable soybean. We investigated a soybean mini core collection composed of 224 germplasm accessions for four yield-related traits in two consecutive years. Based on 1514 single nucleotide polymorphisms (SNPs), genome-wide association studies (GWAS) were conducted using a mixed linear model (MLM).

RESULTS

Extensive phenotypic variation existed in the soybean mini core collection and significant positive correlations were shown among most of traits. A total of 16 SNP markers for PFW, SFW, KP and MCFS were detected in all environments via GWAS. Nine SNP markers were repeatedly identified in two environments. Among these markers, eight were located in or near regions where yield-related QTLs have been reported in previous studies, and one was a novel genetic locus identified in this study. In addition, we conducted candidate gene analysis to the large-effect SNP markers, a total of twelve genes were proposed as potential candidate genes of soybean yield at the R6 stage.

CONCLUSION

These results will be beneficial for understanding the genetic basis of soybean yield at the R6 stage and facilitating the pyramiding of favourable alleles for future high-yield breeding by marker-assisted selection in vegetable soybean.

Utilizing Consumer Perception of Edamame to Guide New Variety Development

Consumption of edamame (vegetable soybeans) has increased significantly in the U.S. over the last 20 years. Although market demand has been increasing, most edamame is still imported from Asian countries. A team of multistate plant-breeding programs in the mid-Atlantic and Southeast U.S. has focused on developing new breeding lines that grow well in the U.S. and deliver what domestic growers, processors and consumers need and expect from their edamame. In our study, sensory evaluation was used to identify edamame genotypes and sensory attributes preferred by consumers to support breeding selection criteria. In the first year (reported as our “screening study”), 20 edamame genotypes were grown in three locations: Newport, AR, and Blacksburg and Painter, VA. In the second year (reported as our “validation study”), 10 edamame genotypes selected after our screening study were grown in Blacksburg and Painter, VA, Portageville, MO, and Stoneville, MS. In both years of research, untrained participants (adults; vegetable consumers not allergic to soy; N ≥ 50) used a traditional 9-point acceptability (hedonic) scale (1 = “dislike extremely”; 9 = “like extremely”) to evaluate overall-liking, aroma, appearance, taste, and texture, and a 5-point scale (1 = “not sweet,” 5 = “extremely sweet”) to evaluate sweetness intensity. Next, participants used a check-all-that-apply (CATA) list of selected sensory terms to describe the sensory characteristics of each edamame sample. Overall acceptability of edamame genotypes was significantly different among all genotypes (p < 0.05). Samples described as “bitter,” “sour” (flavor) or “starchy” (texture) were associated with lower acceptability scores while “salty” and “sweet” (flavor) were correlated with higher acceptability. Sensory data from the screening study were used to select the best genotypes by use of a defined decision process based on the consumer data. The validation study tested the selection decisions and further supported the genotype choices. Sensory evaluation is a powerful tool to direct breeders to improve market acceptability and develop new edamame genotypes. Both screening and validation studies illustrate the significant role of consumer sensory data in support of genotypes targeted for domestic (U.S.) production.

A Modified Roger's Distance Algorithm for Mixed Quantitative-Qualitative Phenotypes to Establish a Core Collection for Taiwanese Vegetable Soybeans

Vegetable soybeans [Glycine max (L.) Merr.] have characteristics of larger seeds, less beany flavor, tender texture, and green-colored pods and seeds. Rich in nutrients, vegetable soybeans are conducive to preventing neurological disease. Due to the change of dietary habits and increasing health awareness, the demand for vegetable soybeans has increased. To conserve vegetable soybean germplasms in Taiwan, we built a core collection of vegetable soybeans, with minimum accessions, minimum redundancy, and maximum representation. Initially, a total of 213 vegetable soybean germplasms and 29 morphological traits were used to construct the core collection. After redundant accessions were removed, 200 accessions were retained as the entire collection, which was grouped into nine clusters. Here, we developed a modified Roger's distance for mixed quantitative-qualitative phenotypes to select 30 accessions (denoted as the core collection) that had a maximum pairwise genetic distance. No significant differences were observed in all phenotypic traits (p-values > 0.05) between the entire and the core collections, except plant height. Compared to the entire collection, we found that most traits retained diversities, but seven traits were slightly lost (ranged from 2 to 9%) in the core collection. The core collection demonstrated a small percentage of significant mean difference (3.45%) and a large coincidence rate (97.70%), indicating representativeness of the entire collection. Furthermore, large values in variable rate (149.80%) and coverage (92.5%) were in line with high diversity retained in the core collection. The results suggested that phenotype-based core collection can retain diversity and genetic variability of vegetable soybeans, providing a basis for further research and breeding programs.

Nutritional Content and Antioxidant Capacity of the Seed and the Epicarp in Different Ecotypes of Pistacia atlantica Desf. Subsp. atlantica

Phenolic compounds are secondary metabolites that occur naturally in all plants. Seeds are among the richest organs of plants in phytochemicals, vitamins and minerals. These compounds and their biological activities are of great importance for human health. This study aimed to analyze the phenolic composition and their antioxidant activity in the seeds and epicarps of six Algerian populations of Pistacia atlantica Desf. subsp. atlantica growing along an aridity gradient from semi-arid to Saharan environmental conditions. Higher phenolic contents were observed in epicarp compared to seeds whatever the ecotype. The highest phenolic content of seeds and epicarps was observed in ecotype of Djelfa and the lowest values in Tiaret (T-Z). Phenolic composition, measured by reversed-phase high-performance liquid chromatography (HPLC), showed that quercetin in epicarp, gallic and chlorogenic acids in seeds were the most present in all ecotypes. Large differences were observed between ecotypes for nutritional values. Seeds were rich in flavonoids, proteins, carbohydrates and essential elements such as potassium, calcium, phosphorus and iron. These results highlighted the potential importance of Atlas pistachio fruits as a source of essential compounds that contribute to human health. Moreover, this underused species may serve a potential source for antioxidant components for alimentation and cosmetics purposes.

Analysis and comparison of seed protein, oil, and sugars in edamame dried using two oven-drying methods and mature soybeans

BACKGROUND

Edamame, a vegetable soybean (Glycine max) grown mainly in Asia, has high nutritional and market value and is a relatively new crop to North America. By 2 years of field trials, we evaluated the seed composition traits in 54 genotypes to analyze the differences and relationship between edamame seeds dried by two oven-drying methods and mature soybeans.

RESULTS

The genotypic differences were significant for all the traits investigated. Significant differences also existed between the two sets of dried edamame and mature seeds. Protein content in mature soybean averaged 426.8 g kg-1 , and 432.8 g kg-1 and 405.6 g kg-1 for shelled-dried and unshelled-dried edamame respectively. Oil content in shelled-dried and unshelled-dried edamame averaged 206.3 g kg-1 and 212.6 g kg-1 respectively, and 195.8 g kg-1 for mature soybean. Sucrose content in mature soybean (60.2 g kg-1 ) was approximately 1.5 and 3 times that of unshelled-dried and shelled-dried edamame respectively. Mature soybean also exhibited the highest concentrations of stachyose and total sugars, followed by unshelled-dried and shelled-dried edamame. The broad-sense heritability estimates of traits in mature soybean (49.41-89.16%) were higher than those of edamame (10.26-78.96%). Higher broad-sense heritability was uncovered for protein and oil, but lower estimates for sugars, fiber, and ash. Positive correlations were detected between the two sets of edamame seeds and mature soybean for protein and oil (r = 0.63-0.88).

CONCLUSION

The results suggest that indirect selection through mature seeds is helpful for the improvement of protein and oil in edamame, whereas the improvement of seed sugars in edamame is more challenging. © 2020 Society of Chemical Industry.

Changes in the sugars, amino acids and organic acids of postharvest spermine-treated immature vegetable soybean (Glycine max L. Merr.) as determined by 1H NMR spectroscopy

Abstract

1H NMR spectroscopy was adopted to determine compositional changes (mainly sugars, organic acids and amino acids) involved in cold-stored immature soybean grains after exogenous spermine treatment. Significant changes of sugars, including sucrose, galactose, myo-inositol, glucose and fructose were detected in soybean after spermine treatment. As for the organic acids related to tricarboxylic acid cycle, the levels of malic and fumaric acids decreased but the level of citric acid increased. However, no significant changes were observed for amino acids in spermine-treated soybeans. By using metabolic profile analysis, a difference was observed between the aging of soybean grains as such and those treated with spermine. This study provides an insight into the accumulation of metabolites in postharvest immature soybeans after exogenous spermine-treatment.

Graphical abstract

The effects of Meloidogyne incognita and Heterodera glycines on the yield and quality of edamame (Glycine max l.) in Arkansas

In 2012, the first domestic commercial edamame processing plant was established in Arkansas and edamame production was contracted out to local growers. Although the state is a major soybean producer, studies of nematode effects on edamame are limited. A survey of nematode genera and density in 64 contracted edamame production fields was conducted in 2013 and 2014. In both years, Meloidogyne and Heterodera were present in less than half of the surveyed fields while Pratylenchus was the most prevalent in 2013 and Helicotylenchus in 2014. A microplot study was conducted in 2014 in two locations to evaluate the effects of root-knot nematode (Meloidogyne incognita, race 3) and soybean cyst nematode (Heterodera glycines, HG type 2.5.7) on plant growth, yield and food quality components of edamame. Yield was the most consistent factor influenced by nematode pressure with increasing nematode population densities resulting in suppressed pod and seed weight. Additionally, seed protein content was reduced in the highest tested population density of H. glycines. In greenhouse studies, 22 advanced edamame breeding lines from the University of Arkansas soybean breeding program were compared with two susceptible commercial cultivars for suitability as hosts for both M. incognita and H. glycines independently. Four lines showed consistent reductions in M. incognita reproduction relative to the commercial cultivars and could represent sources of moderate resistance for development of future root-knot nematode resistant edamame cultivars.

Genome-wide association study of four yield-related traits at the R6 stage in soybean

BACKGROUND

The 100-pod fresh weight (PFW), 100-seed fresh weight (SFW), 100-seed dry weight (SDW) and moisture content of fresh seeds (MCFS) at the R6 stage are crucial factors for vegetable soybean yield. However, the genetic basis of yield at the R6 stage remains largely ambiguous in soybean.

RESULTS

To better understand the molecular mechanism underlying yield, we investigated four yield-related traits of 133 soybean landraces in two consecutive years and conducted a genome-wide association study (GWAS) using 82,187 single nucleotide polymorphisms (SNPs). The GWAS results revealed a total of 14, 15, 63 and 48 SNPs for PFW, SFW, SDW and MCFS, respectively. Among these markers, 35 SNPs were repeatedly identified in all evaluated environments (2015, 2016, and the average across the two years), and most co-localized with yield-related QTLs identified in previous studies. AX-90496773 and AX-90460290 were large-effect markers for PFW and MCFS, respectively. The two markers were stably identified in all environments and tagged to linkage disequilibrium (LD) blocks. Six potential candidate genes were predicted in LD blocks; five of them showed significantly different expression levels between the extreme materials with large PFW or MCFS variation at the seed development stage. Therefore, the five genes Glyma.16g018200, Glyma.16g018300, Glyma.05g243400, Glyma.05g244100 and Glyma.05g245300 were regarded as candidate genes associated with PFW and MCFS.

CONCLUSION

These results provide useful information for the development of functional markers and exploration of candidate genes in vegetable soybean high-yield breeding programs.

Identification of chilling-responsive microRNAs and their targets in vegetable soybean (Glycine max L.)

Chilling stress is a major factor limiting the yield and quality of vegetable soybean (Glycine max L.) on a global scale. In the present study, systematic identification and functional analysis of miRNAs under chilling stress were carried out to clarify the molecular mechanism of chilling resistance. Two independent small RNA libraries from leaves of soybean were constructed and sequenced with the high-throughput Illumina Solexa system. A total of 434 known miRNAs and 3 novel miRNAs were identified. Thirty-five miRNAs were verified by qRT-PCR analysis. Furthermore, their gene targets were identified via high-throughput degradome sequencing. A total of 898 transcripts were targeted by 54 miRNA families attributed to five categories. More importantly, we identified 51 miRNAs differentially expressed between chilling stress and control conditions. The targets of these miRNAs were enriched in oxidation-reduction, signal transduction, and metabolic process functional categories. Our qRT-PCR analysis confirmed a negative relationship among the miRNAs and their targets under chilling stress. Our work thus provides comprehensive molecular evidence supporting the involvement of miRNAs in chilling-stress responses in vegetable soybean.

Determination of the genetic diversity of vegetable soybean [Glycine max (L.) Merr.] using EST-SSR markers

The development of expressed sequence tag-derived simple sequence repeats (EST-SSRs) provided a useful tool for investigating plant genetic diversity. In the present study, 22 polymorphic EST-SSRs from grain soybean were identified and used to assess the genetic diversity in 48 vegetable soybean accessions. Among the 22 EST-SSR loci, tri-nucleotides were the most abundant repeats, accounting for 50.00% of the total motifs. GAA was the most common motif among tri-nucleotide repeats, with a frequency of 18.18%. Polymorphic analysis identified a total of 71 alleles, with an average of 3.23 per locus. The polymorphism information content (PIC) values ranged from 0.144 to 0.630, with a mean of 0.386. Observed heterozygosity (Ho) values varied from 0.0196 to 1.0000, with an average of 0.6092, while the expected heterozygosity (He) values ranged from 0.1502 to 0.6840, with a mean value of 0.4616. Principal coordinate analysis and phylogenetic tree analysis indicated that the accessions could be assigned to different groups based to a large extent on their geographic distribution, and most accessions from China were clustered into the same groups. These results suggest that Chinese vegetable soybean accessions have a narrow genetic base. The results of this study indicate that EST-SSRs from grain soybean have high transferability to vegetable soybean, and that these new markers would be helpful in taxonomy, molecular breeding, and comparative mapping studies of vegetable soybean in the future.

Study on the relevance between beany flavor and main bioactive components in Radix Astragali

Beany flavor is a traditional sensory indicator for evaluating the quality of Radix Astragali (RA or "Huangqi" in Chinese). A RA root with a strong beany flavor is considered to be good quality in Chinese medicine. However, there is neither a study reporting volatile compounds contributing to RA beany flavor nor the relevance between beany flavor and the quality of RA. In this study, we assessed the quantification of beany flavor substance and main bioactive metabolites. The results showed that hexanal was a major volatile component contributing to the beany flavor in RA. The value of hexanal was significantly related to the origin and growth age of RA, indicating that the component could be used as a volatile indicator for the distinction of RA. Statistical analysis further demonstrated that hexanal, astragaloside IV, and total polysaccharides were primary indicators and total isoflavonoids, astragalosides, calycosin, and formononetin were the secondary indicators for quality control of RA. Correlation analysis showed that the level of hexanal was positively associated with the concentration of astragaloside IV and total polysaccharides. Our study demonstrated that aroma is one of the most important quality attributes of RA and will help to understand the role of aroma in quality assessment of traditional Chinese medicines.