Commercial Soybean Varieties Research Articles

Characterization of soy curd residue and full-fat soy flour as protein-based food ingredients

The study investigated the soy curd residue and full-fat soy flour as potential protein-based food ingredients. Standard protocols were used to determine proximate parameters, functional properties, markers of oxidative stability under shelf storage, colour (CIE L* a* b*), and microbial quality of the flours. Commercial Afayak soybean varieties were used to prepare soy curd residue flour and two differently treated soy flours, namely full-fat soy flour and cold-water extracted full-fat soy flour. Findings from the study indicate that processing treatment and storage time significantly (p<0.001) affected the parameters measured. Cold-water extraction of full-fat soy flour resulted in a significantly (p<0.001) higher protein content denoting 1.0, and 1.2-fold than full-fat soy flour and soy curd residue, respectively. Full-fat soy flour showed the highest peroxide, acid, and p-anisidine (p < 0.001) under processing and storage conditions. Soy curd residue was the most oxidatively stable among the samples; however, it was noted that cold-water extraction of full-fat soy had better oxidative stability than full-fat Soy flour. After 12 weeks of storage, peroxide and acid values were below the acceptable limit of 10 mEq/Kg and 0.6 mg/KOH/g, respectively. The study supports the hypothesis that the proximate composition, physicochemical properties, and oxidative stability of soy-based flours are affected by the sample processing method and storage time. The study concludes that the samples characterized in this study are oxidatively stable, protein and energy-rich and may be ideal ingredients for food product development with desirable functional properties.

Identification of Rhizobia Isolated from Nodules of Mexican Commercial Soybean Varieties

Identification of Rhizobia Isolated from Nodules of Mexican Commercial Soybean Varieties

A Sequence Variation in GmBADH2 Enhances Soybean Aroma and Is a Functional Marker for Improving Soybean Flavor.

The vegetable soybean (Glycine max L. Merr.) plant is commonly consumed in Southeast Asian countries because of its nutritional value and desirable taste. A “pandan-like” aroma is an important value-added quality trait that is rarely found in commercial vegetable soybean varieties. In this study, three novel aromatic soybean cultivars with a fragrant volatile compound were isolated. We confirmed that the aroma of these cultivars is due to the potent volatile compound 2-acetyl-1-pyrroline (2AP) that was previously identified in soybean. A sequence comparison of GmBADH1/2 (encoding an aminoaldehyde dehydrogenase) between aromatic and non-aromatic soybean varieties revealed a mutation with 10 SNPs and an 11-nucleotide deletion in exon 1 of GmBADH2 in Quxian No. 1 and Xiangdou. Additionally, a 2-bp deletion was detected in exon 10 of GmBADH2 in ZK1754. The mutations resulted in a frame shift and the introduction of premature stop codons. Moreover, genetic analyses indicated that the aromatic trait in these three varieties was inherited according to a single recessive gene model. These results suggested that a mutated GmBADH2 may be responsible for the aroma of these three aromatic soybean cultivars. The expression and function of GmBADH2 in aromatic soybean seeds were confirmed by qRT-PCR and CRISPR/Cas9. A functional marker developed on the basis of the mutated GmBADH2 sequence in Quxian No. 1 and Xiangdou was validated in an F2 population. A perfect association between the marker genotypes and aroma phenotypes implied that GmBADH2 is a major aroma-conferring gene. The results of this study are potentially useful for an in-depth analysis of the molecular basis of 2-AP formation in soybean and the marker-assisted breeding of aromatic vegetable soybean cultivars.

Oomicide treated soybean seeds reduce early season stand loss to Phytophthora sojae

The causal agent of Phytophthora stem and root rot (PRR), Phytophthora sojae Gerdemann and Kaufman, is a major pathogen of soybean (Glycine max (L.) Merr.). Integrated pest management strategies for PRR consists of planting varieties with effective single-dominant resistance genes (Rps genes), partial resistance (field tolerance) and seed treatments containing oomicides such as ethaboxam and mefenoxam. To investigate the interaction of PRR partial resistance and seed treatment on soybean stand, vigor and yield, soybean plots were inoculated in-furrow with P. sojae isolates able to overcome the Rps genes present in the planted soybean varieties in Michigan in 2018 as well as Michigan, Indiana, and Minnesota in 2019. Nine commercial soybean varieties with contrasting Phytophthora resistance profiles received three different seed treatments: 1) non-treated, 2) base (ipconazole and clothianidin), and 3) Intego Suite (base + ethaboxam and mefenoxam) in Michigan, with four of the same varieties and seed treatments being planted in Indiana and Minnesota. Soybean stand was significantly protected with Intego Suite in the nine varieties tested in Michigan 2018, eight of nine in Michigan 2019, and two of four in Indiana 2019. Significant differences in yield between seed treatments were observed in three varieties of nine in Michigan 2018. The effect of partial resistance on plant health and final yields was not apparent given the supplied company partial resistance scores across locations and years. In conclusion, this study finds that oomicide seed treatments are useful in protecting soybean stand under PRR disease pressure in multiple locations in the Midwest United States.

Selection for yield shifted the proportion of oil and protein in favor of low-energy seed fractions in soybean

Owing to the high contents of oil and protein, soybean [Glycine max L. (Merr.)] seeds are energy-rich. Genetic improvement of soybean yield is linked to the dilution in seed protein; changes in low-energy compounds such as carbohydrates have received less attention. We tested the hypothesis that selection for yield in soybean has shifted seed composition in favor of low-energy compounds. We characterized the dynamics of three seed fractions (protein, oil, and residual) during seed filling in seven commercial soybean varieties released between 1980 and 2013 in a two-year field experiment. Genetic gain in yield was linked with reduced seed energy cost: seed protein concentration decreased by 0.06% yr−1, oil remained stable, and the residual fraction increased by 0.09% yr−1. Seed accumulation of the residual fraction revealed a shorter lag phase and a longer effective filling period for the modern relative to the older soybean varieties. Seed energetic requirement significantly decreased − 0.06% yr−1. Resource availability per seed during the seed-filling period was not limiting across all tested varieties. Further research is warranted on the biochemical nature of the residual fraction, and on the implications of seed composition for future breeding, soybean meal and end uses.

Copy Number Quantification for the Soybean Cyst Nematode Resistance Locus rhg1 in the Soybean Varieties of Taiwan

Disease resistance is one of the most successful strategies in crop protection. For example, the implementation of PI 88788 type resistance, which contains high copy numbers of Resistance to Heterodera glycines 1 (rhg1) loci, into the commercial soybean varieties of the United States has significantly reduced the yield losses caused by soybean cyst nematode (SCN, H. glycines). Vegetable soybean, or edamame, has become a major exporting agricultural product in Taiwan with an annual revenue over $80 million USD since 2017. Several local varieties have been developed to fulfill the market needs such as the traits of flavor and sweetness. However, it remains unclear if the historical breeding programs ever incorporated rhg1 resistance into the varieties of Taiwan. This study applied the TaqMan qPCR method to measure the fluorescent signals specific to the rhg1 locus on the chromosome 18 of soybean, and the ratio of VIC and FAM signals were analyzed to predict the rhg1 copy number in the 21 soybean varieties of Taiwan. The results indicated the copy number and the single nucleotide polymorphisms of the 21 soybean varieties were identical to the susceptible soybean variety ‘Williams 82’. As importation of soybean will be continuously needed to fulfill the market and because SCN is absent in the soybean fields of Taiwan, lacking rhg1 resistance in the local soybean varieties may put the edamame industry at risk and early implementation of SCN resistance in the breeding program, alongside the application of quarantine regulations, will be the key to maintain the SCN-free status and to sustain the edamame industry in Taiwan.

Final Health and Environmental Risk Assessment of Genetically Modified Soybean A5547-127

Soybean A5547-127 expresses the phosphinothricin - N - acetyltransferase (pat) gene from the soil bacterium Streptomyces viridochromogenes. The encoded PAT protein confers tolerance to the active herbicidal substance glufosinate-ammonium. Bioinformatics analyses of the inserted DNA and flanking sequences in soybean A5547-127 have not indicated a potential production of putative harmful proteins or polypeptides caused by the genetic modification. Genomic stability of the functional insert and consistent expression of the pat gene have been shown over several generations of soybean A5547-127. With the exception of the intended changes caused by the trans-genetically introduced trait, data from field trials performed in the USA show that soybean A5547-127 is compositionally, morphologically and agronomically equivalent to its conventional counterpart and other commercial soybean varieties. A repeated dose toxicity study with rats and a nutritional assessment trial with broilers have not revealed adverse effects of soybean A5547-127. These studies indicate that soybean A5547-127 is nutritionally equivalent to and as safe as conventional soybean varieties. The PAT protein produced in soybean A5547-127 does not show sequence resemblance to known toxins or IgE-dependent allergens, nor has it been reported to cause IgE-mediated allergic reactions. Soybean is not cultivated in Norway, and there are no crosscompatible wild or weedy relatives of soybean in Europe. 
 
 Based on current knowledge the VKM GMO Panel concludes that with the intended usage, there are no discernible safety concerns associated with soybean A5547-127 regarding human or animal health or to the environment in Norway.

Final Health and Environmental Risk Assessment of Genetically Modified Soybean MON 89788

Soybean MON 89788 expresses the cp4 epsps gene from the plant pathogenic bacterium Agrobacterium tumefaciens (Rhizobium radiobacter) sp. strain CP4. The encoded enzyme 5enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) protein confers tolerance to the active herbicidal substance glyphosate. Updated bioinformatics analyses of the inserted DNA and flanking sequences in soybean MON 89788 have not indicated a potential production of putative harmful proteins or polypeptides caused by the genetic modification. Genomic stability of the functional insert and consistent expression of the cp4 epsps gene, have been shown over several generations of soybean MON 89788. With the exception of the intended changes caused by the trans-genetically introduced trait, data from several field trials performed in USA and Argentina show that soybean MON 89788 is compositionally, morphologically and agronomically equivalent to its conventional counterpart and other commercial soybean varieties. A sub-chronic feeding study with rats, as well as a nutritional assessment trial with broilers has not revealed adverse effects of soybean MON 89788. These studies indicate that soybean MON 89788 is nutritionally equivalent to, and as safe as conventional soybean varieties. The CP4 EPSPS protein produced in soybean MON 89788 does not show sequence resemblance to known toxins or IgE-dependent allergens, nor has it been reported to cause IgE-mediated allergic reactions. Soybean is not cultivated in Norway, and there are no cross-compatible wild or weedy relatives of soybean in Europe. 
 
 Based on current knowledge, the VKM GMO Panel concludes that with the intended usage, there are no discernible safety concerns associated with soybean MON 89788 regarding human or animal health or to the environment in Norway.

Final Health and Environmental Risk Assessment of Genetically Modified Soybean A2704-12

Soybean A2704-12 expresses the phosphinothricin-N-acetyltransferase (pat) gene, from the soil bacterium Streptomyces viridochromogenes. The encoded PAT protein confers tolerance to the active herbicidal substance glufosinate-ammonium. Bioinformatics analyses of the inserted DNA and flanking sequences in soybean A2704-12 have not indicated a potential production of putative harmful proteins or polypeptides caused by the genetic modification. Genomic stability of the functional insert and consistent expression of the pat gene have been shown over several generations of soybean A2704-12. With the exception of the intended changes caused by the transgenetically introduced trait, data from field trials performed in the USA and Canada show that soybean A2704-12 is compositionally, morphologically and agronomically equivalent to its conventional counterpart and to other commercial soybean varieties. A repeated dose toxicity study in with rats and a nutritional assessment trial with broilers indicate that soybean A2704-12 is nutritionally equivalent to and as safe as conventional soybean varieties. The PAT protein produced in soybean A270412 does not show sequence resemblance to known toxins or IgE-dependent allergens, nor has it been reported to cause IgE-mediated allergic reactions. Soybean is not cultivated in Norway, and there are no cross-compatible wild or weedy relatives of soybean in Europe. 
 
 Based on current knowledge, the VKM GMO Panel concludes that with the intended usage, there are no discernible safety concerns associated with soybean A2704-12 regarding human or animal health or to the environment in Norway.

Common Phytophthora sojae Pathotypes Occurring in South Dakota

Phytophthora root and stem rot, caused by Phytophthora sojae, is an important disease of soybean (Glycine max L.) in South Dakota. Because P. sojae populations are highly diverse and resistance genes deployed in commercial soybean varieties often fail to protect against this pathogen, this study was initiated to determine P. sojae pathotypes occurring in South Dakota. A total of 216 P. sojae isolates were baited from soil collected from 422 soybean fields in 2013 to 2015 and 2017. The pathotype of each isolate was determined by inoculating 10 seedlings of 13 standard soybean P. sojae differential lines using the hypocotyl inoculation technique. Of the 171 pathotyped isolates, 47 unique pathotypes were identified. The virulence complexity of isolates ranged from virulence on one Rps gene (Rps7) to virulence on 13 Rps genes, and mean complexity was 5.2. Harosoy (Rps7), Harlon (Rps1a), Williams 79 (Rps1c), Williams 82 (Rps1k), and Harosoy 13XX (Rps1b) were susceptible to 98, 80, 78, 73, and 72% of the isolates, respectively. These results highlight the highly diverse P. sojae pathotypes in South Dakota and the likely Rps genes to be ineffective in commercial soybean varieties.

The numbers game of soybean breeding in the United States

Abstract: Soybean [Glycine max (L.) Merr.] represents one of the most essential crops to the world’s economy and food security due to its unique seed composition. Public soybean breeding programs in the United States played an important role in developing the genetic basis of American soybean and discovering many economically important traits. After the passage of the Plant Variety Protection Act (PVP) in 1970 and the authorization to patent living matter in 1980, private companies have dominated the market share of commercial soybean varieties and public breeding programs shifted the efforts towards basic and applied research and education of the next generation of plant breeders. The short history of soybean breeding combined with a very narrow genetic basis derived from few ancestors can only make us reflect on all the innovations yet to be unveiled and the multiple possibilities to explore the unique traits that the golden miracle bean offers.

Potential for yield loss reduction and profitability assessment of pesticide control of groundnut leaf miner among soybean genotypes

Groundnut leaf miner (GLM) is currently a threat to soybean production in Uganda due to the great yield losses as a result of the severe damage it causes on leaves leading to reduced photosynthetic area. GLM is a fairly new pest on soybean in Uganda, having initially been observed in soybean fields in 2011 in eastern Uganda. The objective of this study was to determine the yield loss caused by the groundnut leaf miner and effectiveness and profitability of commonly used pesticides for the control of the groundnut leaf miner (Aproaerema modicella Deventer) (GLM), when tested with popular soybean (Glycine max) genotypes grown in Uganda. In a split plot RCBD design, pesticide protection (treated vs. untreated) formed the main plots; and six commercial soybean varieties (Maksoy 1N, 2N, 3N, 4N, 5N; and Namsoy 4M) as subplots. The study was done in two locations in eastern Uganda (Iki Iki District Agricultural Training and Information Centre (Iki Iki DATIC) and National Semi-Arid Resources Research Institute, Serere (NaSARRI) with two planting rounds at Iki Iki. These sites were chosen because they are hot spots for GLM. GLM severity and soybean yield were significantly affected by the pesticide protection. Overall, percentage grain yield losses caused by GLM on the different soybean varieties ranged from 37.3% to 65.7% and the highest loss was displayed by Maksoy 5N. Grain yield loss recorded at Iki Iki DATIC (53.1%) was remarkably higher than that recorded at the NaSARRI (49.1%). Economic analysis showed marginal returns to be dependent on location, with the Iki Iki DATIC having 0.6 and NaSARRI 1.1. This study has shown that the groundnut leaf miner, a recently emergent pest of soybean is becoming a big threat to soybean production and that chemical control alone may not be economical in managing the pest.Key words: Aproaerema modicella, Glycine max, marginal returns, Uganda

Whole-genome re-sequencing reveals the impact of the interaction of copy number variants of the rhg1 and Rhg4 genes on broad-based resistance to soybean cyst nematode.

SummarySoybean cyst nematode (SCN) is the most devastating plant‐parasitic nematode. Most commercial soybean varieties with SCN resistance are derived from PI88788. Resistance derived from PI88788 is breaking down due to narrow genetic background and SCN population shift. PI88788 requires mainly the rhg1‐b locus, while ‘Peking’ requires rhg1‐a and Rhg4 for SCN resistance. In the present study, whole genome re‐sequencing of 106 soybean lines was used to define the Rhg haplotypes and investigate their responses to the SCN HG‐Types. The analysis showed a comprehensive profile of SNPs and copy number variations (CNV) at these loci. CNV of rhg1 (GmSNAP18) only contributed towards resistance in lines derived from PI88788 and ‘Cloud’. At least 5.6 copies of the PI88788‐type rhg1 were required to confer SCN resistance, regardless of the Rhg4 (GmSHMT08) haplotype. However, when the GmSNAP18 copies dropped below 5.6, a ‘Peking’‐type GmSHMT08 haplotype was required to ensure SCN resistance. This points to a novel mechanism of epistasis between GmSNAP18 and GmSHMT08 involving minimum requirements for copy number. The presence of more Rhg4 copies confers resistance to multiple SCN races. Moreover, transcript abundance of the GmSHMT08 in root tissue correlates with more copies of the Rhg4 locus, reinforcing SCN resistance. Finally, haplotype analysis of the GmSHMT08 and GmSNAP18 promoters inferred additional levels of the resistance mechanism. This is the first report revealing the genetic basis of broad‐based resistance to SCN and providing new insight into epistasis, haplotype‐compatibility, CNV, promoter variation and its impact on broad‐based disease resistance in plants.

Risk assessment of new sequencing information for genetically modified soybean BPS-CV127-9.

The GMO Panel has previously assessed genetically modified (GM) soybean BPS‐CV127‐9. This soybean was found to be as safe and nutritious as its conventional counterpart and commercial soybean varieties with respect to potential effects on human and animal health and the environment in the context of its intended uses. On 16 February 2018, European Commission requested EFSA to analyse new nucleic acid sequencing data and updated bioinformatics data for GM soybean BPS‐CV127‐9 and to indicate whether the previous conclusions of the GMO Panel on safety of GM soybean BPS‐CV127‐9 remain valid. The new sequencing data indicated a two nucleotide difference in the unannotated Arabidopsis genomic DNA sequence downstream of the 3′ untranslated region of the ahasl (also referred to as csr1‐2) gene as compared to the sequencing data originally provided. One of these nucleotide differences reported in the new nucleic acid sequencing data from GM soybean event BPS‐CV127‐9 was shown to be already present in the original plant material used for the risk assessment. However, for the other nucleotide difference reported, no evidence could be provided to differentiate between a sequencing error and point‐mutation. With the exception of bioinformatics analyses, the studies performed for the risk assessment of the single event soybean BPS‐CV127‐9 remain valid. The new sequencing data and the bioinformatics analyses performed on the new sequence did not give rise to safety issues. Therefore, EFSA concludes that the original risk assessment of soybean BPS‐CV127‐9 remains valid.

Variation in Seed Allergen Content From Three Varieties of Soybean Cultivated in Nine Different Locations in Iowa, Illinois, and Indiana.

Soybean (Glycine max) is an important food stock, and also considered an allergenic food with at least eight well characterized allergens. However, it is a less prevalent allergen source than many other foods and is rarely life-threatening. Soybean is incorporated into commonly consumed foods, and therefore, the allergens pose a potential concern for individuals already sensitized. The protein profile of soybean can be affected by several factors including genetic and environmental. To investigate how soybean allergen content may be affected by genetics and/or environment, nine soy allergens were quantified from three commercial soybean varieties grown at nine locations in three states within a single climate zone in North America; Iowa, Illinois, and Indiana, United States. Quantitation was achieved using liquid chromatography-selected reaction monitoring (LC-SRM) tandem mass spectrometry with AQUA peptide standards specific to the nine target allergens. Quantitation of allergen concentration indicated that both genetics and location affected specific allergen content. Seven of the nine allergens were significantly influenced by genetics, with the exceptions of glycinin G4 and KTI 3. The allergens P34, Gly m Bd 28k, glycinin G3, and KTI 1 showed statistically significant impact from location as well, but at a lower threshold of significance compared with genetics (cultivar/variety). This dataset contributes to our understanding of the natural variation of endogenous allergens, as it represents a sampling of soybeans grown in a controlled, distributed plot design under agronomic conditions common for commercial soybean food and feed production. The aim was to build upon our recent understanding of how allergens are expressed as part of the overall soybean proteome.

Mogućnost primene 24-epibrasinolida za smanjenje fitotoksičnosti kod zajedničke primene tifensulfuron-metila i imazamoksa u soji

The applicability of 24-epibrassinolide for reducing phytotoxicity during combined treatments of soybean with thifensulfuron-methyl and imazamox was examined. Tests were conducted in three commercial soybean varieties (Valjevka, Galina and Galeb) on fields of the PKB Co. at Lepusnica and Glogonjski Rit over three vegetation seasons. Commercial products of thifensulfuron-methyl, imazamox and 24-epibrassinolide were used in the trials. The products were applied in combinations, using the recommended application rates at the soybean growth stage of third trifoliate. Phytotoxicity was assessed 14 and 30 days after treatment, and grain yield of each soybean variety was measured at the end of each vegetation season. The combination of thifensulfuron-methyl and imazamox was found to be toxic to soybean in all three seasons, and symptoms of phytotoxicity included: chlorosis and dark red venation of leaves, delayed development of young leaves, and stunted growth. Phytotoxicity was significantly lower in the fields treated with 24-epibrassinolide. Also, the combination of thifensulfuron-methyl, imazamox and 24-epibrassinolide was associated with higher soybean grain yield, compared to the combination of thifensulfuron-methyl and imazamox.

Yield associated traits correlate with cytokinin profiles in developing pods and seeds of field-grown soybean cultivars

While lab and greenhouse based studies have long indicated that cytokinins (CK) promote yield increases in soybean (Glycine max L.), it is not known if the relationship would be valid under more complex field conditions. Thus, an ambitious CK metabolite analysis was undertaken involving long-term field trials of commercial and historical soybean varieties to determine if differences between CK profiles are related to variation in yield performance. Twenty-seven cultivars were evaluated in this study representing a wide range of performance and assessed for 12 agronomically important plant and seed parameters under field conditions. Identification and quantification of 14 forms of CK was undertaken by high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) at three stages of reproductive development that are critical for yield determination (R4–R6). This revealed a substantial increase in CK levels, especially the highly metabolically active free bases, in the high yielding cultivars of soybean. Significant correlations between yield components and the most active CK form, tZ (trans-Zeatin), were detected at both R4 and R5 stages. A similar trend was observed for cZ (cis-Zeatin), indicating a possible role of both zeatin isomers in pod and early seed development. Positive, significant relationships between yield and cytokinins were maintained also at R6 stage; however, a switch in hormone profiles and increased levels of isopentenyl adenine (iP) types of CK in high yielding cultivars suggested that the presence of iP derivatives allowed developing seeds to maintain their active role in sink organs and attract assimilates during the seed filling phases, when the metabolism of the maturing plant was generally slowing down. Results suggested that cytokinin metabolites or their associated genes, may serve as a valuable, early indicators of yield performance in marker-assisted breeding programs for soybean or be manipulated through gene editing techniques.

Nutritional composition analysis for beta-carotene-enhanced transgenic soybeans (Glycine max L.)

Nutritional composition is important for assessing the safety of genetically modified (GM) crops for human consumption. Three beta-carotene-enhanced soybean lines were developed by introducing the β-conglycinin promoter::Phytoene synthase-2A-Carotene desaturase/t35S gene cassette into the genome of the commercial Kwangan (Glycine max L.) soybean variety. Transgenic soybeans were successfully detected on beta-carotene productions ranged from 170.47 to 213.58 µg/g. Comparative assessments of nutrition were conducted with 3 transgenic soybeans, their non-GM counterpart, and several commercial soybean varieties. Results indicated that most levels of proximate, fatty acids, amino acids, and vitamins showed non-significant differences between transgenic soybeans and their counterpart, and fit within the reference ranges established for other commercial soybeans and Organization for Economic Cooperation and Development Guidelines. However, significant differences on levels of crude fat, carbohydrate, δ-tocopherol, and oleic acid of transgenic soybeans comparing to those of non-transgenic counterpart Kwangan cannot eliminate the influences of transgene insertion. Alternations on compositions should be definite by further studies, such as transcriptome and metabolome profiling.

In Vitro Regeneration Potential of Seven Commercial Soybean Cultivars (Glycine max L.) for Use in Biotechnology

Abstract This work is aimed to evaluate in vitro regeneration potential of seven commercial soybean varieties Bohemians, Cardiff, Gallec, Merlin, Moravians, Naya and Silensia (Glycine max L.) cultivated in Central Europe. Our results showed the half-seeds could be effectively used as an explant source for all tested cultivars. The regeneration was initiated on the media containing growth regulators 1.67 mg.l-1 BAP and 0.25 mg.l-1 GA3. Within the first five days culture, green chlorophyll-containing explants were observed with frequency from 18.3% to 55.9%. Two weeks later, the explants responded by production of calli with the efficiency up to 83.0%. First shoots appeared after 2–3 weeks of subculture on the media. The soybean regeneration showed to be genotype-dependent with variable efficiencies from 5.7% (cv. Naya) to 37.7% (cv. Gallec). The cultivars Cardiff, Merlin and Gallec appear to be the most promising candidates for further biotechnological use. Application of antioxidants such as L-cysteine, dithiothreitol and sodium thiosulfate does not have effect on the explant regeneration for the first five days.

Molecular Identification of Dominant Cultivars of Soybean Using Simple Sequence Repeat Markers

Molecular identity of dominant cultivars of soybean needs to complement the morphological descriptors, which are insufficient and influenced by environment, for protecting the interest of breeders and maintaining the genetic purity. In the present investigation, genomic DNA of six commercial Indian soybean varieties viz. JS95-60, JS93-05, NRC7, JS97-52, NRC37, JS335 was amplified using ten simple sequence repeat (SSR) markers, which were selected based upon the relatively higher polymorphic information content (PIC) value observed after polymorphism survey of 46 soybean genotypes through 58 SSR markers. PCR analysis showed nine polymorphic SSR primers which could differentiate unambiguously all the six varieties. Maximum similarity was observed between NRC7, JS93-05 and JS95-60. Two unique alleles amplified in each of the two varieties namely JS335 and NRC37 and four unique alleles in JS97-52 unambiguously differentiated them from the remaining varieties. Morphologically similar varieties JS93-05 and JS95-60 could be differentiated distinctly by primer pair Satt181, while NRC7 could be distinguished from both JS93-05 and JS95-60 through Sct_199. Results also showed that these nine polymorphic markers could distinguish the dominant cultivars from six non-trading varieties, which further confirmed the utility of nine SSR primers for protecting the breeders’ rights and maintaining the purity of dominant cultivars during seed production programme.