Isoflavone Content In Soybean Research Articles

Crosstalk between ethylene and melatonin activates isoflavone biosynthesis and antioxidant systems to produce high-quality soybean sprouts

Isoflavone, which are mainly found in soybeans, are a secondary metabolite with a variety of physiological functions. In recent years, increasing the isoflavone content of soybeans has received widespread attention. Although ethephon treatment significantly increased isoflavone content in soybean sprouts, it also had a certain inhibitory effect on the growth of sprouts. Melatonin (MT), as a new type of plant hormone, not only alleviated the damage caused by abiotic stress to plants, but also promoted the synthesis of secondary metabolites. In this study, we aimed to elucidate the mechanism of exogenous MT in regulating the growth and development, and the metabolism of isoflavone in soybean sprouts under ethephon treatment. The results indicated that MT alleviated the adverse effects of ethephon treatment on soybean sprouts by increasing the activities of superoxide dismutase, peroxidase, catalase, and the expression of their corresponding genes, as well as decreased the content of malondialdehyde and hydrogen peroxide. In addition, MT further increased the isoflavone content by up-regulating the expression level of isoflavone synthesis genes and increased the activities of phenylalanine ammonia-lyase and cinnamic acid 4-hydroxylase under ethephon treatment. This study provided technical support and reference value for the production of high-quality soybean sprouts to a certain extent.

Effects of shading, soil moisture, fertilizations and sowing time on isoflavone content of soybean seed in Hokkaido

ABSTRACT Aiming to produce soybean seeds with high yield and high isoflavone content in Hokkaido, which has cool weather, we evaluated the effects of shading, soil moisture, fertilizations (K,N,P,Mo) and sowing time on yield and seed isoflavone content using mainly a high-isoflavone variety, Yukipirika. Shading treatments of 50 % and 70 % during the seed filling stage in a greenhouse decreased both yield and isoflavone content. Applying four soil moisture treatments from pF 1.5 to pF 2.8 in the seed filling stage in a greenhouse gave a positive correlation between soil moisture and both yield and isoflavone content. K fertilization treatments with different amount and various types of fertilizers were conducted in fields at medium or high level of K2O in soils typical of Hokkaido uplands. The additional K treatments did not increase yield or isoflavone content significantly in the field experiments. N (urea foliar application) treatments in fields did not affect yield and isoflavone content significantly. And P (phosphite root application) and Mo (seed treatment) in fields did not change isoflavone content, either. Sowing two weeks and four weeks later than the standard sowing time in a field decreased the yield but did not change the isoflavone content. From a practical application perspective, for producing soybean seeds with high isoflavone contents and high yield in Hokkaido, it is effective to plant at a standard time with a normal amount of fertilizer in fields with minimum shade and to maintain the soil moisture at well-watered levels during the seed filling stage.

Changes in Isoflavonoid and Flavonoid Content in Soybean Leaves Affected by UV-B or Copper

Abstract The production of antioxidant flavonoids is an important aspect of plant defence mechanisms under stress conditions. The hypothesis of increased antioxidant flavonol quercetin and isoflavone content in soybean leaves subjected to UV-B irradiation and copper toxicity was proposed, and their accumulation was investigated using HPLC analysis. However, the accumulation of antioxidant quercetin was not induced by either UV-B irradiation or copper treatment. UV-B irradiation strongly induced isoflavone aglycones, mainly genistein, daidzein, formononetin, and to a lesser extent, biochanin A. Isoflavone glycosides, genistin and daidzin were also induced. Copper treatment, whether applied to leaves or root media, resulted in the accumulation of genistin and its malonylated form, whereas aglycones were only slightly affected. The higher accumulation of genistein over daidzein after copper treatment could be related to the higher chelating ability of genistein and its glycosides. Soybean isoflavones, which possess antioxidant and chelating properties, rather than flavonols, play a crucial role in the plant‘s defence mechanisms against both UV-B irradiation and copper toxicity.

Identification of the long InDels through whole genome resequencing to fine map of qIF05-1 controlling seed isoflavone content in soybean (Glycine max L. Merr.)

Soybean seed isoflavone can provide health and nutrition benefits for human which is a kind of secondary metabolite. In our previous study, a stable quantitative trait loci (QTL) qIF05-1 controlling seed isoflavone content in soybean had been detected on chromosome (Chr.) 05 in a recombinant inbred line (RIL) population from a cross from Huachun 2×Wayao. In this study, the parental lines were re-sequenced using the Illumina Solexa System with deep-coverage, a total of 63099 polymorphic long Insertions and Deletions (InDels) (≥15 bp) were identified between the parents Huachun 2 and Wayao, which were unevenly distributed on 20 chromosomes of soybean, varying from 1826 in Chr12 to 4544 in Chr18. 10002 long InDels (15.85% of total) were located in genic regions, including 1139 large-effect long InDels which resulted in truncated or elongated protein sequences. In the qIF05-1 region, there was 68 long InDels being detected between the two parents. Using progeny recombination experiment and genotype analysis, the qIF05- 1 locus was mapped into a 102.2-kb genomic region, 12 genes are located in this region contained 12 genes. By RNA-seq data analysis, genome sequence comparison and functional validation through ectopic expression into Arabidopsis, Glyma.05G208300 (described as GmEGL3), a basic helix-loop-helix (bHLH) transcription factor in plants, might be the likely confirmed gene in qIF05-1. These long InDels are a kind of complementary genetic method for QTL fine mapping and can facilitate genetic studies and molecular assisted selection breeding in soybean.

Developmental dynamic transcriptome and systematic analysis reveal the major genes underlying isoflavone accumulation in soybean.

Soy isoflavone, a class of polyphenolic compounds exclusively occurred in legumes, is an important bioactive compound for both plants and human beings. The outline of isoflavones biosynthesis pathway has been drawn up basically in the previous research. However, research on the subject has been mostly restricted to investigate the static regulation of isoflavone content in soybean, rather than characterize its dynamic variation and modulation network in developing seeds. In this study, by using eight recombinant inbred lines (RIL), the contents of six isoflavone components in the different stages of developing soybean seeds were determined to characterize the dynamic variation of isoflavones, and the isoflavones accumulation pattern at physiological level was investigated. Meanwhile, we integrated and analyzed the whole genome expression profile of four lines and 42 meta-transcriptome data, based on the multiple algorithms. This study: 1) obtained 4 molecular modules strongly correlated with isoflavone accumulation; 2) identified 28 novel major genes that could affect the accumulation of isoflavones in developing seeds free from the limitation of environments; 3) discussed the dynamic molecular patterns regulating isoflavones accumulation in developing seed; 4) expanded the isoflavone biosynthesis pathway. The results not only promote the understandings on the biosynthesis and regulation of isoflavones at physiological and molecular level, but also facilitate to breed elite soybean cultivars with high isoflavone contents.

Classification and discrimination of soybean (Glycine max (L.) Merr.) genotypes based on their isoflavone content

Isoflavones are phytoestrogens with various types of biological activity. Soybean (Glycine max (L.) Merr.) is the most abundant source of isoflavones in human nutrition. The present study aims to classify the different soybean genotypes according to their isoflavone contents. HPLC analysis of isoflavone content in 22 soybean genotypes was performed. The average content of individual isoflavones in the genotypes analyzed ranged from 2.8 μg/g to 1069,9 μg/g while the most abundant component among the 22 genotypes was malonyl-genistin. The majority of isoflavones had a significantly higher concentration (p < 0.05) in the hybrid genotypes compared to parental genotypes implying heterosis. The principal component analysis (PCA) on isoflavone content and composition, including results in 83 genotypes, was conducted. The contents of daidzein and genistein were positively correlated, which could be explained by their biosynthetic pathways. Using the PCA, analyzed genotypes divided into six coherent groups regarding their specific isoflavone content. Malonyl-genistin and malonyl-daidzin were the most abundant components. Moreover, the significance of the cultivation year on the isoflavone content in soybean was pointed out. The overall results suggested the possibility of selection of suitable soybean extracts according to the content of malonyl-genistin.

Overexpressing GmCHI1A increases the isoflavone content of transgenic soybean (Glycine max (L.) Merr.) seeds

Isoflavones, which are secondary metabolites synthesised through the phenylpropanoid pathway, play important roles in many essential physiological processes of the soybean plant. Isoflavones are well-known for their antioxidant, antimicrobial, anti-inflammatory and anticancer activities; however, soybean plants contain very low amount of isoflavone. Therefore, increasing isoflavone content is one of major concerns in soybean research. An effective approach to enhance isoflavone content in soybean is by overexpression of the Glycine max chalcone isomerase 1A (GmCHI1A) gene. In this study, the GmCHI1A gene was transformed into soybean plants and the T2 generation was selected for high isoflavone content (daidzein, genistein) in transgenic soybean germs. GmCHI1A gene expression was enhanced in T1 transgenic lines, which led to an increase in recombinant CHI1A (rCHI1A) protein content. In soybean germs of the T2 transgenic lines, the content of daidzein and genistein increased from 166.46 to 187.23% and from 329.77 to 463.93%, respectively. Four T2 transgenic soybean lines (T2-1, T2-4, T2-21 and T2-24) with high daidzein and genistein content were selected for future progeny evaluation.

품종 및 가공방법에 따른 콩 특성 및 Isoflavone 변화

품종 및 가공방법에 따른 콩 특성 및 Isoflavone 변화

Novel process of hydration, followed by incubation and thermal processing, for high isoflavone bioconversion in soybeans

The potentially bioavailable aglyconic isoflavone content of soybeans was increased by a process based on the controlled hydration of whole beans, followed by an incubation step and cooking. For developing the process, the effects of three operation variables: temperature, intermittent soaking and incubation time on the isoflavone profile of the processed soybeans were assessed. By hydrating the whole beans under controlled conditions (54 °C; 15 rpm for a rotating soaking basket) and holding the beans for an appropriate incubation time, it was possible to substantially increase the total aglycone content from (μmol·10−2·g−1) ~5 in the raw, to ~95 in the processed soybean. A conventional thermal treatment (1 kg⋅cm−2, 5 min), necessary to attain the nutritional and sensory characteristics, produced additional hydrolysis of glucosides, accounting for extra 14% of total aglycone yield. The entire process avoided the need to grind the bean and permitted an overall 21.8-fold increase (per-mole basis) conversion of all forms of isoflavone glucosides to aglycones, particularly to the (S)-equol precursor, daidzein, and with minimal back-diffusion or leaching to the outside medium.

Fine-mapping of QTLs for individual and total isoflavone content in soybean (Glycine max L.) using a high-density genetic map.

Fifteen stable QTLs were identified using a high-density soybean genetic map across multiple environments. One major QTL, qIF5-1, contributing to total isoflavone content explained phenotypic variance 49.38, 43.27, 46.59, 45.15 and 52.50%, respectively. Soybeans (Glycine max L.) are a major source of dietary isoflavones. To identify novel quantitative trait loci (QTL) underlying isoflavone content, and to improve the accuracy of marker-assisted breeding in soybean, a valuable mapping population comprised of 196 F7:8-10 recombinant inbred lines (RILs, Huachun 2×Wayao) was utilized to evaluate individual and total isoflavone content in plants grown in four different environments in Guangdong. A high-density genetic linkage map containing 3469 recombination bin markers based on 0.2×restriction site-associated DNA tag sequencing (RAD-seq) technology was used to finely map QTLs for both individual and total isoflavone contents. Correlation analyses showed that total isoflavone content, and that of five individual isoflavone, was significantly correlated across the four environments. Based on the high-density genetic linkage map, a total of 15 stable quantitative trait loci (QTLs) associated with isoflavone content across multiple environments were mapped onto chromosomes 02, 05, 07, 09, 10, 11, 13, 16, 17, and 19. Further, one of them, qIF5-1, localized to chromosomes 05 (38,434,171-39,045,620bp) contributed to almost all isoflavone components across all environments, and explained 6.37-59.95% of the phenotypic variance, especially explained 49.38, 43.27, 46.59, 45.15 and 52.50% for total isoflavone. The results obtained in the present study will pave the way for a better understanding of the genetics of isoflavone accumulation and reveals the scope available for improvement of isoflavone content through marker-assisted selection.

The characteristics of gmchi gene isolated from soybean cultivars with different isoflavone content

In this study, isoflavone content of five soybean varieties disseminated grown in North Vietnam have been surveyed, and the GmCHI gene encoding chalcone isomerase, a key enzyme in metabolizing synthetic isoflavone in soybeans, was analyzed. Content of isoflavone (daidzein, genistein) in 3-day-old germinated seeds of soybean cultivar DT26 was the highest (64.27 mg/100g) and higher 2.18 times and 2.45 times compared with DT84 and DT2008 respectively. GmCHI gene isolated from mRNA of the soybean cultivars DT26, DT51, DT2008, DT84 is 657 nucleotides in length, encoding 218 amino acids. Similarity coefficient of nucleotide sequence of GmCHI gene of four soybean DT26, DT51, DT2008, DT84 ranged from 96.8% to 98.9% and similar to those of NM_001248290 on GenBank from 98% to 99%. Genetic distances of DT26 compared with DT51 DT26, DT2008, DT84 and other varieties based on nucleotide sequences of GmCHI gene was 19.3% and based on the amino acid sequence deduced was 4.4%. Coding region of GmCHI gene has been used as a material for design transfomation vector for the improvement of isoflavone content in soybean by gene transfer technique.

Mapping isoflavone QTL with main, epistatic and QTL × environment effects in recombinant inbred lines of soybean.

Soybean (Glycine max (L.) Merr.) isoflavone is important for human health and plant defense system. To identify novel quantitative trait loci (QTL) and epistatic QTL underlying isoflavone content in soybean, F5:6, F5:7 and F5:8 populations of 130 recombinant inbred (RI) lines, derived from the cross of soybean cultivar ‘Zhong Dou 27′ (high isoflavone) and ‘Jiu Nong 20′ (low isoflavone), were analyzed with 95 new SSR markers. A new linkage map including 194 SSR markers and covering 2,312 cM with mean distance of about 12 cM between markers was constructed. Thirty four QTL for both individual and total seed isoflavone contents of soybean were identified. Six, seven, ten and eleven QTL were associated with daidzein (DZ), glycitein (GC), genistein (GT) and total isoflavone (TI), respectively. Of them 23 QTL were newly identified. The qTIF_1 between Satt423 and Satt569 shared the same marker Satt569 with qDZF_2, qGTF_1 and qTIF_2. The qGTD2_1 between Satt186 and Satt226 was detected in four environments and explained 3.41%-10.98% of the phenotypic variation. The qGTA2_1, overlapped with qGCA2_1 and detected in four environments, was close to the previously identified major QTL for GT, which were responsible for large a effects. QTL (qDZF_2, qGTF_1 and qTIF_2) between Satt144-Satt569 were either clustered or pleiotropic. The qGCM_1, qGTM_1 and qTIM_1 between Satt540-Sat_244 explained 2.02%–9.12% of the phenotypic variation over six environments. Moreover, the qGCE_1 overlapped with qGTE_1 and qTIE_1, the qTIH_2 overlapped with qGTH_1, qGCI_1 overlapped with qDZI_1, qTIL_1 overlapped with qGTL_1, and qTIO_1 overlapped with qGTO_1. In this study, some of unstable QTL were detected in different environments, which were due to weak expression of QTL, QTL by environment interaction in the opposite direction to a effects, and/or epistasis. The markers identified in multi-environments in this study could be applied in the selection of soybean cultivars for higher isoflavone content and in the map-based gene cloning.

Additional Quantitative Trait Loci and Candidate Genes for Seed Isoflavone Content in Soybean

Seed isoflavone content of soybean (Glycine max L. Merr.) is a trait of moderate heritablity and an ideal target for marker selection. To date over 20 QTL have been identified underlying this trait among seven populations. The objectives of this study were to identify additional QTL and candidate genes controlling isoflavone content in a set of recombinant inbred line (RIL) populations of soybean grown in two different seasons. Variations of isoflavones namely daidzein, glycitein and genistein contents over two growing seasons and locations suggests that isoflavones are influenced by both genes and environments. Six QTL were identified on five different chromosomes (Chr) or linkage groups (LG) that controlled daidzein (Chr_2/LG-M; Chr_17a/LG-D2), glycitein (Chr_2/LG-D1b; Chr_8/LG-A2) and genistein (Chr_8/LG-A2; Chr_12/LG-H) respectively in the seeds grown in season 2010. Two QTL were identified for daidzein (Chr_6/LG-C2; Chr_13b/LG-F), two QTLs for glycitein (Chr_1/LG-D1a; Chr_17c/LG-D2) and five QTLs for genistein (Chr_3/ LG-N; Chr_8/LG-A2; Chr_9/LG-K; Chr_18/LG-G) in the seeds of the 2011 growing season. Genes located within QTL confidence intervals were retrieved and gene ontology (GO) terms were used to identify those related to the flavonoid biosynthesis process. Twenty six candidate genes were identified that may be involved in isoflavones accumulation in soybean seeds.

콩잎 품종에 따른 이화학적 특성 비교 및 콩잎 분말을 첨가한 두부 개발

본 연구에서는 품종에 따른 콩잎의 이화학적 특성을 살펴보고자, 4종류 콩잎(대원, 대풍, 황금, 서리태)을 이용하여 평가하였으며, 콩잎 분말의 활용방안을 모색하기 위해 콩잎 분말을 첨가한 두부를 개발하여 그 이용 가능성을 알아보았다. 콩잎의 이화학적 특성을 살펴본 결과, 품종별로 유의적인 차이를 나타내었다(p<0.05). 콩잎은 대부분 탄수화물로 이루어져있으며, K, Ca, Mg, Na, P, Fe 등의 무기질이 함유되어 있는데 상대적으로 칼륨 함량이 높음을 확인할 수 있었다. Isoflavone 함량은 모든 품종에서 daidzein 함량이 genistein 함량 보다 함량이 높게 나타났고 특히, 대풍콩잎에서 유의적으로 높은 함량을 나타내었다(p<0.05). 대풍콩잎 분말의 첨가량(0, 0.1, 0.2, 0.3%)을 달리하여 두부를 제조하여 품질 특성을 살펴본 결과, 수율은 두부 간에 유의적인 차이를 보이지 않았다. 명도(L)와 적색도(a)는 대조군에 비해 유의적으로 낮아지는 경향을 보였으나 황색도(b)는 콩잎 첨가 수준이 증가할수록 점점 증가하는 경향을 보였다. 조직감 특성은 유의적인 차이를 보이지 않았으나, 경도(hardness)는 대조군에 비해 콩잎을 첨가한 두부에서 높은 경향을 보였으며 이는 관능평가 결과에서도 비슷한 추이를 나타냈다. 두부의 외관, 맛, 향, 조직감에 대하여 특성 강도를 평가한 결과, 콩잎의 첨가수준이 증가할수록 대조군에 비해 고소한 맛은 덜한 반면, 두부의 색, 향, 조직감은 강하게 평가되었다. 기호도 평가에서는 콩잎을 첨가한 두부가 대조군에 비해 높게 평가되었고, 0.2% 첨가 두부에서 전반적인 기호도가 가장 높은 것으로 나타났다. 이상의 결과를 종합해보면 콩잎 분말 첨가는 전체적인 관능평가에 긍정적인 영향을 미치며, 특히 콩잎 분말 0.2%가 두부의 기호도를 높일 수 있을 것이라고 사료된다. 본 연구를 통하여 콩잎의 이화학적 특성은 품종에 따라 유의적인 차이가 있음을 확인하였으며 식품 소재로서의 콩잎 분말의 이용가능성 또한 확인할 수 있었다. 이러한 연구 결과는 콩잎 분말의 식품학적 가치를 향상시키고 기능성 소재로서의 이용 가능성을 증진시킬 수 있는 기초자료가 될 것으로 기대되며, 나아가 기능성 식품 개발에 크게 기여할 것으로 사료된다. The objectives of this study were to investigate the physicochemical characteristics of soybean leaves in different cultivars and to develop a soybean curd prepared with soybean leave powder as a functional food. Four cultivars (Daewonkong leaf, Daepungkong leaf, Hwangguemkong leaf, and Seoritae leaf) were selected for this experiment. A significant difference was observed in the proximate composition of soybeans leaves (p<0.05). Soybean leaves had the highest content of carbohydrates. The mineral composition and isoflavone content in soybean leaves were significantly different among the cultivars (p<0.05). In particular, Daepongkong leaf had the highest content of genistein, daidzein, and total isoflavones. This study was also conducted to determine the quality characteristics of a soybean curd developed from daepongkong leaf with various concentrations (0, 0.1, 0.2, and 0.3%) of soybean leaf powder (SLP). The soybean curd yield rate increased according to the level of SLP added, whereas the L and a color values decreased. In the sensory evaluation, intensity scores for color, after taste, leafy taste, and chewiness were highest for the 0.3% soybean curd. The soybean curd with 0.2% SLP soybean milk attained the highest overall acceptability score. These results showed that soybean leaf was preferred over soybean curd containing 0.2% soybean leaf powder.

Simultaneous Enhancement of Free Isoflavone Content and Antioxidant Potential of Soybean by Fermentation with Aspergillus oryzae

In order to determine the fungal strain and fermentation period which produce the highest antioxidant activity of fermented soy product, soybean was fermented with Aspergillus oryzae NL 5 isolated from Korean traditional meju produced in Sunchang Yeastopia Land in Korea, and was subjected to analyzing isoflavone profiles and assaying antioxidant activity. Antioxidant potential of the samples was evaluated by ferric reducing antioxidant power assay, 2,2'-azinobis (2-ethylbenzthiazoline-6-sulfonic acid) radical scavenging activity and total phenolic contents. In addition, antioxidant assay using fluorescent probes, 2',7'-dichlorofluorescin diacetate and dihydroethidium, in HepG2 cells was conducted for the samples. The results showed that both high isoflavone variety Aga 3 and medium isoflavone variety Daewon of soybean fermented with Asp oryzae NL5 for 4 to 5 d showed the highest increase in free isoflavone contents, together with the highest antioxidant activity. In conclusion, the antioxidant activity of fermented soy was proportional to the concentration of free isoflavones, and was significantly influenced by total isoflavone content of soybean variety and fermentation period. Practical Application: Isoflavone profile and antioxidant capacity of soybean were widely variable during fermentation with Asp oryzae, and thereby it is recommended that meju (or koji) preparation condition, in particular, fermentation time is carefully optimized to maximize the antioxidant capacity of soy products fermented by Asp oryzae.

8-Hydroxygenistein formation of soybean fermented with Aspergillus oryzae BCC 3088

The isoflavone content of soybean was studied by incubated Thai native soybean (Glycine max (L) Merr, SJ.2) with Aspergillus oryzae BCC 3088. The changes of the isoflavone analogue content were analysed by HPLC. Mass spectrometry was used to confirm the presence of substances in fermented soybean with the authentic standards. After fermentation, total glycosides content of soybean fermented with A. oryzae BCC 3088 decreased but the proportion of aglycone markedly increased. As for the increases of isoflavone aglycone during the fermentation, the proportion of aglycones in total isoflavones was markedly higher in soybeans fermented with A. oryzae BCC 3088 than was those from uninoculated soybean. Furthermore, 8-hydroxygenistein (8-OHG) was found at the fourth day of fermentation. Therefore, fermentation of soybean with A. oryzae BCC 3088 results in higher levels of isoflavone aglycones and their corresponding, 8-OHG, which may enhance more health benefits than unprocessed soybean. Key words: Aspergillus oryzae, fermented soybean, isoflavone, 8-hydroxygenistein.

Determination of Phytoestrogen Composition in Soybean Cultivars in Serbia

The growing clinical interest and use of soybean-based food products and extracts to increase dietary phytoestrogen intake have led to medical interest in the precise determination of the phytoestrogen composition of soybean products. We have analyzed the composition of these compounds in 20 domestic and introduced varieties of genetically non-modified soybean genotypes grown under the same agroecological conditions. The isoflavone content of soybeans cultivated in this region of Serbia has not been previously reported. The assays were performed, after extraction with methanol-water (8:2, v/v), by C18 reversed phase high-performance liquid chromatography coupled with photodiode array detection. The total phytoestrogen concentration was found to be between 2.24 and 3.79 mg g(-1) dry bean weight. The total concentration of daidzein and its derivatives ranged from 0.96 to 1.82 mg g(-1), total glyciteines from 0.34-0.53 mg g(-1), and all genistein derivatives from 0.86-1.67 mg g(-1) dry bean weight. Given the high biological potency of phytoestrogens and their metabolic conversion products, our data suggest that phytoestrogen content screening could be a useful tool in the selection of soybean genotypes with improved health promoting characteristics.

Genotype × Environment Interaction and Stability for Isoflavone Content in Soybean

Isoflavones are naturally occurring compounds found in soybean [Glycine max (L.) Merr.]. Soybean isoflavone, as a quantitative trait, is subject to significant genotype × environment interaction, which makes breeding for this trait difficult. Thirty F4:7 soybean lines, derived from crosses of ‘RCAT Angora’ × CK‐01 and ‘Heinong 35’ × RCAT Angora were classified within each population as high, intermediate, or low isoflavone. The lines, parents, and two maturity checks were grown in four locations in 2005 and six locations in 2006 across Ontario and Quebec, Canada. Isoflavone content of the mature seed was determined by near‐infrared reflectance. The effects of genotype, environment, and the genotype × environment (G × E) interaction were significant. Consistently performing genotypes from the two populations were identified by several stability parameters. Genotype–genotype × environment (GGE) biplot demonstrated an ability to provide information on both the genotypes and the environments in which they were evaluated. The identification of genotypes with consistent placement in either the high‐ and low‐isoflavone classes suggested that breeding for relative isoflavone content in soybean is possible, although breeding for absolute stability remains a challenge, given the large environmental influence on soybean isoflavone levels.

Identification of QTL underlying isoflavone contents in soybean seeds among multiple environments

Soybean isoflavones are valued in certain medicines, cosmetics, foods and feeds. Selection for high-isoflavone content in seeds along with agronomic traits is a goal of many soybean breeders. The aim of the study was to identify the quantitative trait loci (QTL) underlying seed isoflavone content in soybean among seven environments in China. A cross was made between 'Zhongdou 27', a soybean cultivar with higher mean isoflavone content in the seven environments (daidzein, DZ, 1,865 microg g(-1); genistein, GT, 1,614 microg g(-1); glycitein, GC, 311 microg g(-1) and total isoflavone, TI, 3,791 microg g(-1)) and 'Jiunong 20', a soybean cultivar with lower isoflavone content (DZ, 844 microg g(-1); GT, 1,046 microg g(-1); GC, 193 microg g(-1) and TI, 2,061 microg g(-1)). Through single-seed-descent, 130 F(5)-derived F(6) recombinant inbred lines were advanced. A total of 99 simple-sequence repeat markers were used to construct a genetic linkage map. Seed isoflavone contents were analyzed using high-performance liquid chromatography for multiple years and locations (Harbin in 2005, 2006 and 2007, Hulan in 2006 and 2007, and Suihua in 2006 and 2007). Three QTL were associated with DZ content, four with GT content, three with GC content, and five with TI content. For all QTL detected the beneficial allele was from Zhongdou 27. QTL were located on three (DZ), three (GC), four (GT) and five (TI) molecular linkage groups (LG). A novel QTL was detected with marker Satt144 on LG F that was associated with DZ (0.0014 > P > 0.0001, 5% < R (2) < 11%; 254 < DZ < 552 microg g(-1)), GT (0.0027 > P > 0.0001; 4% < R (2) < 9%; 262 < GT < 391 microg g(-1)), and TI (0.0011 > P > 0.0001; 4% < R (2) < 15%; 195 < TI < 871 microg g(-1)) across the various environments. A previously reported QTL on LG M detected by Satt540 was associated with TI across four environments and TI mean (0.0022 > P > 0.0001; 3% < R (2) < 8%; 182 < TI < 334 microg g(-1)) in China. Because both beneficial alleles were from Zhongdou 27, it was concluded that these two QTL would have the greatest potential value for marker-assisted selection for high-isoflavone content in soybean seed in China.

Genetic Analysis of Embryo, Cytoplasm and Maternal Effects and Their Environment Interactions for Isoflavone Content in Soybean [ Glycine max (L.) Merr.

Abstract Soybean seed products contain isoflavones (genistein, daidzein, and glycitein) that display biological effects when ingested by humans and animals. These effects are species, dose and age dependent. Therefore, the content and quality of isoflavones in soybeans is a key factor to the biological effect. Our objective was to identify the genetic effects that underlie the isoflavone content in soybean seeds. A genetic model for quantitative traits of seeds in diploid plants was applied to estimate the genetic main effects and genotype x environment ( GE) interaction effects for the isoflavone content ( IC) of soybean seeds by using two years experimental data with an incomplete diallel mating design of six parents. Results showed that the IC of soybean seeds was simultaneously controlled by the genetic effects of maternal, embryo, and cytoplasm, of which maternal genetic effects were most important, followed by embryo and cytoplasmic genetic effects. The main effects of different genetic systems on IC trait were more important than environment interaction effects. The strong dominance effects on isoflavone from residual was made easily by environment conditions. Therefore, the improvement of the IC of soybean seeds would be more efficient when selection is based on maternal plants than that on the single seed. Maternal heritability (65.73%) was most important for IC, followed by embryo heritability (25.87%) and cytoplasmic heritability (8.39%). Based on predicated genetic effects, Yudou 29 and Zheng 90007 were better than other parents for increasing IC in the progeny and improving the quality of soybean. The significant effects of maternal and embryo dominance effects in variance show that the embryo heterosis and maternal heterosis are existent and uninfluenced by environment interaction effects.