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Hoffman, D. D., Diers, B. W., Hartman, G. L., Nickell, C. D., Nelson, R. L., Pedersen, W. L., Cober, E. R., Graef, G. L., Steadman, J. R., Grau, C. R., Nelson, B. D., del Rio, L. E., Helms, T., Anderson, T., Poysa, V., Rajcan, I., and Stienstra, W. C. 2002. Selected soybean plant introductions with partial resistance to Sclerotinia sclerotiorum. Plant Dis. 86:971-980. Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is a major soybean (Glycine max) disease in north-central regions of the United States and throughout the world. Current sources of resistance to Sclerotinia stem rot express partial resistance, and are limited in number within soybean germ plasm. A total of 6,520 maturity group (MG) 0 to IV plant introductions (PIs) were evaluated for Sclerotinia stem rot resistance in the United States and Canada in small plots or in the greenhouse from 1995 to 1997. Selected PIs with the most resistance were evaluated for resistance in the United States and Canada in replicated large plots from 1998 to 2000. The PIs in the MG I to III tests in Urbana, IL were evaluated for agronomic traits from 1998 to 2000. The selected PIs also were evaluated with an excised leaf inoculation and petiole inoculation technique. After the 1995 to 1997 evaluations, all but 68 PIs were eliminated because of their susceptibility to Sclerotinia stem rot. In field tests in Urbana, higher disease severity in selected MG I to III PIs was significantly (P < 0.05) associated with taller plant heights and greater canopy closure. All other agronomic traits evaluated were not associated or were inconsistently associated with disease severity. MG I to III PIs 153.282, 189.931, 196.157, 398.637, 417.201, 423.818, and 561.331 had high levels of resistance and had canopies similar to the resistant checks. The resistance ratings from the petiole inoculation technique had a high and significant (P < 0.01) correlation with disease severity in the MG I and II field tests. The partially resistant PIs identified in this study can be valuable in incorporating Sclerotinia stem rot resistance into elite germ plasm.

HS-171 is a large-seeded edamame food-grade soybean genotype [Glycine max. (L.) Merr.] with yellow hilum, low oil, and high protein and sucrose concentrations. It is adapted to the areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity rating of 2.6.

Soybean improvement via plant breeding has been critical for the success of the crop. The objective of this study was to quantify genetic change in yield and other traits that occurred during the past 80 yr of North American soybean breeding in Maturity Groups (MGs) II, III, and IV. Historic sets of 60 MG II, 59 MG III, and 49 MG IV soybean cultivars, released from 1923 to 2008, were evaluated in field trials conducted in 17 U.S. states and one Canadian province during 2010 to 2011. Averaged over 27 MG II and MG IV and 26 MG III site-years of data, the estimated rates of yield improvement during the 80 yr were 23 kg ha yr for MGs II and III, and 20 kg ha yr for MG IV cultivars. However, a two-segment linear regression model provided a better fit to the data and indicated that the average current rate of genetic yield gain across MGs is 29 kg ha yr. Modern cultivars yielded more than old cultivars in all environments, but particularly in high-yielding environments. New cultivars in the historic sets used in this study are shorter in height, mature later, lodge less, and have seeds with less protein and greater oil concentration. Given that on-farm soybean yields in the United States are also increasing at a rate of 29 kg ha yr, it can be inferred that continual release of greater-yielding cultivars has been a substantive driver of the U.S. on-farm realized yield increases.

HS-151 is a lipoxygenase free food grade soybean line (Glycine max. L.) with large seed size, high protein content, yellow hilum, and satisfactory food processing quality. It is adapted to areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity of 2.2 (MG 2.2).

HS-162 is a 7S β-conglycinin α′ and 11S glycinin A4 null food-grade soybean (Glycine max L. Merr.) line with high protein concentration, large seed, yellow hilum, and excellent food processing qual...

HS-161 is a 7S β-conglycinin α′ and 11S glycinin A3 null food-grade soybean line (Glycine max (L.) Merr.) with high protein concentration, yellow hilum, and fair food processing quality. It is adap...

Soybean mutant lines that differ in 11S glycinin and 7S β-conglycinin seed storage protein subunit compositions were developed. These proteins have significant influence on tofu quality. The molecular mechanisms underlying the mutant lines are unknown. In this study, gene-specific markers for five of the glycinin genes (Gy1 to Gy5) were developed using three 11S null lines, two A(4) null Japanese cultivars, Enrei and Raiden, and a control cultivar, Harovinton. Whereas gene-specific primers produced the appropriate products in the control cultivar for the Gy1, Gy2, Gy3 and Gy5 genes, they did not amplify in mutants missing the A(1a)B(2), A(2)B(1a), A(1b) B(1b), and A(3)B(4) subunits. However, ecotype targeting induced local lesions in genomes (EcoTILLING) and sequencing analysis revealed that the absence of the A(4) peptide in the mutants is due to the same point mutation as that in Enrei and Raiden. Selection efficiency of the gene-specific primer pairs was tested using a number of breeding lines segregating for the different subunits. Primer pairs specific to each of the Gy1, Gy2, Gy3, and Gy5 genes can be used to detect the presence or absence of amplification in normal or mutant lines. The Gy4 null allele can be selected for by temperature-switch PCR (TS-PCR) for identification of the A(4) (G4) null genotypes. In comparison to protein analysis by SDS-PAGE, gene-specific markers are easier, faster and more accurate for analysis, they do not have to use seed, and can be analyzed at any plant growth stage for marker-assisted selection.

Accurate normalization of gene expression with qRT-PCR depends on the use of appropriate reference genes (RGs) for the species under a given set of experimental conditions. Multiple RGs for gene expression analysis of soybean exposed to heavy metal stress treatment have not been reported in the literature. In this study, we evaluated the expression stability of ten candidate RGs in leaves, roots and stems of two soybean cultivars exposed to cadmium (Cd). Based on the geNorm and NormFinder analysis, ACT3, PP2A, ELF1B and F-box were the most stable RGs in these gene expression studies. In contrast, G6PD, UBC2, TUB, and ELF1A were the most variable ones and should not be used as RGs in these experimental conditions.

The effect of soy protein subunit composition on the acid-induced aggregation of soymilk was investigated by preparing soymilk from different soybean lines lacking specific glycinin and β-conglycinin subunits. Acid gelation was induced by glucono-δ-lactone (GDL) and analysis was done using diffusing wave spectroscopy and rheology. Aggregation occurred near pH 5.8 and the increase in radius corresponded to an increase in the elastic modulus measured by small deformation rheology. Diffusing wave spectroscopy was also employed to follow acid gelation, and data indicated that particle interactions start to occur at a higher pH than the pH of onset of gelation (corresponding to the start of the rapid increase in elastic modulus). The protein subunit composition significantly affected the development of structure during acidification. The onset of aggregation occurred at a higher pH for soymilk samples containing group IIb (the acidic subunit A3) of glycinin, than for samples prepared from Harovinton (a commercial variety containing all subunits) or from genotypes null in glycinin. The gels made from lines containing group I (A1, A2) and group IIb (A3) of glycinin resulted in stiffer acid gels compared to the lines containing only β-conglycinin. These results confirmed that the ratio of glycinin/β-conglycinin has a significant effect on gel structure, with an increase in glycinin causing an increase in gel stiffness. The type of glycinin subunits also affected the aggregation behavior of soymilk.

Although soy proteins are known to have a deleterious effect on gluten thermosetting gelation, the causes are still poorly understood. Different sources of soy protein isolates (SPI) were used to investigate the interactions between gluten and soy proteins during hydro-thermal treatments. Commercial SPI and isolates prepared from soybean lines with different subunit composition were used to study the influence of protein denaturation and subunit composition on thermoset gel formation. Rapid Visco Analyser analysis showed that replacement of gluten with more than 1% SPI decreased the peak viscosity and interfered with formation of thermoset gels. However, peak viscosity was higher for 11% gluten + 2% SPI than for 11% gluten alone, suggesting a cooperative effect. After heating and cooling, 11% gluten + 2% SPI rich in A1 and A2 subunits formed a coherent thermoset gel suggesting that the cysteine residue content of soy proteins can affect gel formation.

Phytophthora root rot (PRR) of soybean (Glycine max (L.) Merr.) is the second most important cause of yield loss by disease in North America, surpassed only by soybean cyst nematode (Wrather et al. in Can J Plant Pathol 23:115-121, 2001). Tolerance can provide economically useful disease control, conditioning partial resistance of soybean to PRR. The aims of this study were to identify new quantitative trait loci (QTL) underlying tolerance to PRR, and to evaluate the effects of pyramided or stacked loci on the level of tolerance. A North American cultivar 'Conrad' (tolerant to PRR) was crossed with a northeastern China cultivar 'Hefeng 25' (tolerant to PRR). Through single-seed descent, 140 F2:5 and F2:6 recombinant inbred lines were advanced. A total of 164 simple sequence repeat (SSR) markers were used to construct a genetic linkage map. The percentage of seedling death was measured over 2 years (2007 and 2008) in the field at four naturally infested locations in Canada and China following additional soil infestation and in the greenhouse following inoculation with Phytophthora sojae isolate. A total of eight QTL underlying tolerance to PRR were identified, located in five linkage groups (F, D1b+w, A2, B1, and C2). The phenotypic variation contributed by the loci ranged from 4.24 to 27.98%. QPRR-1 (anchored in the interval of SSR markers Satt325 and Satt343 of LG F), QPRR-2 (anchored in the interval of Satt005 and Satt600 of LG D1b+w), and QPRR-3 (anchored in the interval of Satt579 and Sat_089 of LG D1b+w) derived their beneficial allele from 'Conrad'. They were located at chromosomal locations known to underlie PRR tolerance in diverse germplasm. Five QTL that derived beneficial alleles from 'Hefeng 25' were identified. The QTL (QPRR-1 to QPRR-7) that were detected across at least three environments were selected for loci stacking and to analyze the relationship between number of tolerance loci and disease loss percentage. The accumulation of tolerance loci was positively correlated with decreases in disease loss percentage. The pyramid of loci underlying tolerance to PRR provided germplasm useful for crop improvement by marker-assisted selection and may provide durable cultivar tolerance against the PRR disease.

Daily consumption of cadmium (Cd) contaminated foods poses a risk to human health. Cultivar selection is an important method to limit Cd uptake and accumulation; however, analyzing grain Cd concentration is costly and time-consuming. Developing markers for low Cd accumulation will facilitate marker assisted selection (MAS). Inheritance studies using a threshold value of 0.2 mg kg(-1) for low and high and an F(2:3) population showed that low Cd accumulation in soybean seed is under the control of a major gene (Cda1, proposed name) with the allele for low accumulation being dominant. A recombinant inbred line (RIL) population (F(6:8)) derived from the cross AC Hime (high Cd accumulation) and Westag-97 (low Cd accumulation) was used to identify the DNA markers linked to Cda gene(s) or quantitative trait loci (QTLs) controlling low Cd accumulation. We screened 171 simple sequence repeat (SSR) primers that showed polymorphism between parents on the 166 RILs. Of these, 40 primers were newly developed from the soybean genomic DNA sequence. Seven SSR markers, SatK138, SatK139, SatK140 (0.5 cM), SatK147, SacK149, SaatK150 and SattK152 (0.3 cM), were linked to Cda1 in soybean seed. All the linked markers were mapped to the same linkage group (LG) K. The closest flanking SSR markers linked to Cda1 were validated using a parallel population (RILs) involving Leo x Westag-97. Linked markers were also validated with diverse soybean genotypes differing in their seed Cd concentration and showed that SSR markers SatK147, SacK149, and SattK152 clearly differentiated the high and low Cd accumulating genotypes tested. To treat Cd uptake as a quantitative trait, QTL analysis using a linkage map constructed with 161 markers identified a major QTL associated with low Cd concentration in the seeds. The QTL was also mapped to the same location as Cda1 on LG-K. This QTL accounted for 57.3% of the phenotypic variation. Potential candidate genes (genes with known or predicted function that could influence the seed Cd concentration) like protein kinase, putative Adagio-like protein, and plasma membrane H(+)-ATPase were found to be located in the locus of interest. Of the four SSR markers located in the region, SattK152 was localized in the plasma membrane H(+)-ATPase gene. SSR markers closely linked to Cda1 in seeds of soybean were identified and have potential to be used for MAS to develop low Cd accumulating cultivars in a breeding program.

Of 87 short-season soybean cultivars evaluated for reactions to three races (1, 3, and 5) of Phytophthora sojae Kaufmann and Gerdemann, 29 showed resistance to at least one of the three races. These resistant sources may be used for pyramiding Rps genes and deployment of P. sojae resistant soybean cultivars in Canada. Key words: Soybean, Glycine max, phytophthora root and stem rot, Phytophthora sojae

The influence of soy protein subunit composition on the particle size distribution and solid content of soymilk and various supernatant fractions was investigated. A well-established seed variety (Harovinton), containing all protein subunits, and eleven null soybean genotypes lacking specific glycinin and β-conglycinin subunits were investigated, to determine the effect of protein composition on the physico-chemical characteristic of soymilk. Soymilk made from Harovinton and soybean lines null in glycinin showed significantly higher total solid yields than the other genotypes evaluated. Soymilks prepared from soybeans null for glycinin or lacking glycinin's group I (A 1 , A 2 ) showed a smaller particle size distribution compared to soybean lines containing glycinin. In general, unheated soymilk made from lines having glycinin showed a bimodal size distribution with large particles, with a decrease in the particle size distribution after heating and heating with homogenization. The results of this work will help in the evaluation of breeding lines with a specific protein composition tailored to a specific processing functionality.

A possible solution to stability problems is to genetically reduce the content of linolenic acid in soybean seed. RG10 is a low linolenic acid line (< 25 g/kg) produced by ethyl methane sulfonate (EMS) treatment of the low linolenic acid EMS mutant line C1640. The objective of this study was to determine the molecular basis of the low linolenic acid trait in RG10. Sequence analyses of mutant RG10 and wild-type OX948 ω-fatty acid desaturase (Fad3) genes showed that the low level of linolenic acid in RG10 is likely a result of mutations in two Fad3 genes. A mutation in the Fad3A gene introduces a stop codon in exon 6 that would prematurely terminate translation and a second mutation in the 5' splice site of intron 5 of the Fad3B gene may result in abnormal mRNA splicing products. Both mutations would result in a non-functional enzyme. Molecular markers developed for these mutations should simplify and accelerate introgression of the RG10-based low linolenic acid trait into elite soybean cultivars.

Soy protein isolates (SPI) were prepared from 12 soybean lines grown in Harrow, Ontario and by-products (fibers and wheys) from SPI making were saved. The identification and quantification of soluble sugars in defatted flours, fibers and wheys were carried out using high-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) and with a colorimetric method for uronic acids. Defatted flours and fibers were acid hydrolyzed, then analyzed by HPAEC-PAD for monosaccharide composition. The results showed varietal differences in the carbohydrate composition suggesting different applications for these defatted flours and their SPI by-products.

This study focussed on the evaluation of thermal denaturation at three different stages during soy protein isolation and the effect of subunit composition on the formation of heat-induced soy protein gels. Soy protein isolates (SPI) were prepared from 12 high protein lines, Harovinton variety and 11 derived null-lines which lacked specific glycinin (11S) and β-conglycinin (7S) protein subunits. Protein denaturation during SPI processing was monitored by differential scanning calorimetry (DSC). The results showed that hexane extraction of oil from soybean flours at 23 °C or 105 °C did cause changes in protein conformation. Rheological measurements showed that lines with different subunit compositions and 11S:7S ratio had distinctive gelation temperatures and resulted in gels with different network structures. All lines formed particulate gels at 11% protein. The 11S:7S ratio was not correlated to final stiffness, measured as the storage modulus G′, of SPI gels. Lower gelation temperatures were usually observed for 7S-rich lines. The absence of A3 and the combination of A1, A2 and A4 subunits of 11S fraction may suggest the formation of stiffer gels. A more detailed study of the frequency dependence of G′ for the various networks formed also indicated that differences in subunit composition influenced the network structures.

The effect of heat treatment at 95–100 °C for 5 min and homogenization on the physicochemical properties of soymilk was studied, determining the particle size distribution and the amount and type of protein present after step-wise centrifugation. Differential scanning calorimetry of soy protein showed three thermal transitions for unheated soymilk at 54, 70 and 94 °C, which were attributed to 2S, 7S and 11S, respectively. These thermal transitions were absent from heated (and homogenized) soymilk. Unheated soymilk showed a large average particle size, a broad size distribution, and significant protein precipitation with centrifugation. Heating of soymilk decreased the particle size distribution and improved its stability. Homogenization also resulted in a decrease in particle size, with a narrower size distribution compared to heated soymilk. During step-wise centrifugation changes in the ratios of 11S (glycinin) and 7S (β-conglycinin) in the supernatants were noted, and they depended on the treatments applied to soymilk. Transmission electron microscopy observations showed the distribution of the colloidal particles in soymilk and helped further identify the differences after heating and heating with homogenization.

Broad tolerance to phytophthora root rot (PRR) caused by Phytophthora sojae has become an important goal for the improvement of soybean (Glycine max) because of the rapid spread of races that defeat the available resistance genes. The aim of this research was to identify the location of quantitative trait loci (QTL) in ‘Conrad’, a soybean cultivar with broad tolerance to many races of P. sojae. A PRR susceptible breeding line ‘OX760-6-1’was crossed with Conrad. Through single-seed-descent, 112, F2 derived, F7 recombinant inbred lines (RILs) were advanced. A total of 39 random amplified polymorphic DNA bands (RAPDs) and 89 type 1 microsatellite (simple sequence repeat; SSR) markers were used to construct a genetic linkage map. In the greenhouse, RILs were inoculated with four P. sojae isolates (three from China and one from Canada). Disease was measured as the percent of dead plants 20 days after germination in P. sojae inoculated vermiculite in the greenhouse. Three QTLs (QGP1, QGP2, QGP3) for PRR tolerance in the greenhouse were detected using WinQTLCart 2.0 with a log-likelihood (LOD) score 27.14 acquired through permutations (1,000 at P ≤ 0.05). QGP1 (near Satt509) was located at linkage group F and explained 13.2%, 5.9%, and 6.7% of the phenotypic variance for tolerance to the JiXi, JianSanJiang and ShuangYaShan isolates, respectively. QGP2 (near Satt334) was located in a different interval on linkage group F and explained 5.1% and 2.4% of the phenotypic variance for JiXi and ShuangYaShan isolates, respectively. QGP3 was located on linkage group D1b + W (near OPL18800/SCL18659) and explained 10.2% of the phenotypic variance for Woodslee isolate. QGP1 and QGP2 appeared to be associated with PRR tolerance across a range of isolates but QGP3 was active only against the Woodslee isolate. At Woodslee and Weaver (in Ontario) in 2000, the interval associated with QGP3 explained 21.6% and 16.7% of phenotypic variance in resistance to PRR, respectively and was referred as QFP1. The identified QTLs would be beneficial for marker assistant selection of PRR tolerance varieties against both China and North America P. sojae races.

‘Conrad’, a soybean cultivar tolerant to Phytophthora root rot (PRR), and ‘OX760-6-1’, a breeding line with low tolerance to PRR, were crossed. F2 derived recombinant inbred lines were advanced to F6 to generate a population through single-seed descent. This population was used to identify quantitative trait loci (QTLs) influencing PRR tolerance in ‘Conrad’. A total of 99 simple sequence repeat (SSR), or microsatellite, markers that were polymorphic and clearly segregated in the F6 mapping population were used for QTL detection. Based on the data of PRR in the field at two planting locations, Woodslee and Weaver, for the years 2000 and 2001, one putative QTL, designated as Qsatt414-596, was detected using MapMaker/QTL. Qsatt414-596 was flanked by two SSR markers from the linkage group MLG J, Satt414 and Satt596. Satt414 and Satt596 were also detected to be significantly (P

The protein quality of 11 null and 2 tofu soybean genotypes were determined from their total protein content, their amino acid composition, and their glycinin and β-conglycinin contents. There were highly significant differences (P

Seed-size uniformity is an important grading factor in soya beans affecting value. Currently, it is determined by visual inspection. Image analysis-based seed-size measurements were used to predict size uniformity of soya bean samples. Linear discriminant function models and artificial neural network classifiers were developed to classify samples in two uniformity classes (uniform or not uniform in size) using various size distribution parameters as measures of size uniformity. Both methods of classification performed equally well with an agreement in excess of 84% with the visual assessment of samples.

Tofu was made, using two coagulants, from soybean lines which lacked specific glycinin and β-conglycinin protein subunits and the quality evaluated to determine the effects of specific protein subunits. The group IIb (A3) glycinin subunit played the major role in contributing to tofu firmness, regardless of coagulant, while the group IIa (A4) subunit had a negative effect on tofu quality in 2002. Soybeans with the group I (A1A2) subunit resulted in tofu with textural properties about one-third higher, expressed as a percent of Harovinton’s values, than tofu prepared from soybeans without the group I subunit. The individual components of group I had contradictory effects on GDL tofu quality in 2002, with the A1 subunit having a negative effect and A2 having a major positive effect. Lack of the α′ subunit of β-conglycinin increased gel hardness relative to the complete 7S protein.

Soybean [Glycine max (L.) Merrill] seeds contain isoflavones, which have been associated with positive health effects in human adults but a negative effect on infants. Increasing or decreasing isoflavone content in the seed would be desirable; however, it is not known what impact this would have on agronomic and other seed quality traits. The main objective of this study was to determine if isoflavone content in soybean seeds was associated with changes in agronomic and seed quality traits. Recombinant inbred lines (RILs) with high (n = 35), intermediate (n = 35), and low (n = 35) isoflavone content, were selected from three F 4:5 populations grown in 2000 and planted at three locations in southern Ontario in 2002. There were significant differences among populations, environments, and their interaction for isoflavone content. High and low phenotypic classes were significantly different for maturity in all three populations. Despite a positive correlation between yield and isofiavones, several RILs with decreased isoflavone content (970 μg g -1 ) were identified with yields (4222 kg ha -1 ) comparable to high-yielding cultivars. Isoflavone content had minimal effects on oil content, seed quality, and weight. Population 1 showed a significant negative association between isoflavone and protein content, whereas Pop. 2 and Pop. 3 did not. RILs were identified with high isoflavone and protein content ranging from 1746 to 1851 μg g -1 and 431 to 442 g kg -1 , respectively. It was possible to develop soybean with desirable isoflavone content in the seed and superior agronomic and seed quality traits.

To improve oxidative stability of soybean oil and reduce off-flavours, we previously developed low linolenic acid, lipoxygenase-free (LLA.3lx) soybean germplasm. The objectives of this study were to characterize the patterns of inheritance and determine the relationships between the low linolenic acid (LLA) trait derived from the lines RG10 and PI 361088B and seed lipoxygenase nulls (3lx) from a triple null line OX948 that were used to create the new LLA.3lx germplasm. Reciprocal crosses between RG10 and OX948 and between PI 361088B and OX948 were made and populations derived from them were evaluated for their fatty acid profiles and seed lipoxygenases (LX) at the F2, F5 and F6 generations. Both RG10 and PI 361088B contain a single gene that controls linolenic acid (LA) content with alleles acting in an additive manner. No significant cytoplasmic effects were observed on LA content. The LLA trait was highly heritable in both RG10 × OX948 (RO) and PI 361088B × OX948 (PO) crosses and stable in different environments (Belize and Ontario, Canada). The three seed LX were each controlled by single genes, but lipoxygenase 1 (Lx1) and lipoxygenase 2 (Lx2) were tightly linked. No significant correlations were observed between LA content and seed LX. The simple and independent inheritance of LA and seed LX in these crosses should simplify breeding for soybean cultivars that are resistant to oxidative degradation. Key words: Soybean, linolenic acid, lipoxygenase, inheritance, trait relationships

Three soy protein isolates were prepared from two commercial defatted soybean flours (SG and ADM) and flour indigenously prepared from soybeans grown in Ontario (ON). Denaturation degree and protein composition of three isolates as measured by DSC and SDS–PAGE were not different significantly, but remarkable differences in ANS surface hydrophobicity and turbidity were noticed. Heat induced gelling properties of these soy protein isolates were examined by small deformation oscillatory rheological test. The critical gelling concentrations of the two isolates from commercial soy flours (SG and ADM) in distilled water were 90 mg/ml, much lower than 110 mg/ml for ON. The effect of type and concentration of salts on the gelling properties of the three protein isolates were also examined. In 1 mol/L NaCl solution, ADM had the higher gel strength than SG. It was found that the increase in gel strength of ON by addition of NaSCN was much greater than that in NaCl solution. N-Ethylmaleimide (NEM) was observed to increased the gel strength for all soy protein isolates examined despite its sulfhydryl groups blocking function. It is suggested that a non-heat aggregation of protein which led to turbidity development was responsible for the inferior gelling property of ON while the different gelling behavior between SG and ADM could be attributed to their difference in ANS surface hydrophobicity.

A simple sequence repeat (SSR) marker composed of a tetra nucleotide repeat is tightly linked to a major gene of common bean (Phaseolus vulgaris L.) conferring resistance to common bacterial blight (CBB) incited by Xanthomonas axonopodis pv. phasoli (Xap). This SSR is located in the third intron region of the common bean nitrate reductase (NR) gene, which is mapped to linkage group (LG) H7, corresponding to LG B7 of the bean Core map. Co-segregation analysis between the SSR marker and CBB resistance in a recombinant inbred line (RIL) population demonstrated a tight linkage between the NR gene-specific marker and the major gene for CBB resistance. In total, the marker explained approximately 70% of the phenotypic variation in the population. Because it is co-dominant, this SSR marker should be more efficient for marker-assisted selection (MAS) than dominant/recessive random amplified polymorphic DNA (RAPD) or sequence characterized amplified region (SCAR) markers that have been developed, especially for early generation selection.

A rapid and efficient analytical method was developed to distinguish and to quantify two major saponin precursors in soybeans; soyasapogenol A, contributing to the undesirable sensory characteristics, and soyasapogenol B, representing group B and E saponins, which have chemoprotective properties. Aqueous ethanolic extraction (80 % v/v) yielded the highest recovery of saponin from finely ground soybean powder. Acid hydrolysis of extracted saponin in 8 % HCl in anhydrous methanol at 75 C° for 3 hrs cleaved the attached sugar moietie(s) completely from the triterpene aglycones and produced no artifacts. Resultant soyasapogenols were isolated using solid phase extraction and chromatograms of high resolution were obtained by HPLC equipped with evaporative light scattering detector (ELSD). Histochemical analysis revealed that soyasapogenols are mainly concentrated in the axis of seed compared with cotyledon and seed coat. To determine the distribution of soyasapogenol A and B in soybean, 10 advanced food-grade soybean lines were grown in 1999 at four locations in Ontario. In general, total soyasapogenol content in soybeans was 0.2±0.02 %. Soyasapogenol B content (1480±200 μg/g) was 2.5 to 4.5-fold higher than soyasapogenol A content (479±72 μg/g). A significant variation in soyasapogenol content was observed among the cultivars tested. INTRODUCTION The presence of saponins in soybean has attracted considerable interest owing to both health benefits and adverse sensory characteristics. Soybean saponins are heat-stable glycosides and comprise a hydrophobic aglycone (triterpenoid sapogenin) linked to one or more hydrophilic monoor oligosaccharide moiety (Lasztity et al., 1998). Soyasaponins are classified into three groups (A, B, and E) based on their respective aglycone moieties (Tsukamoto et al., 1993). Group A acetylated saponins present in soybean, are implicated as the compounds mostly responsible for the undesirable taste (Okubo et al., 1992) while group B and E saponins have health benefits. Group B and E saponins are indicated to possess inhibitory activity against the infection of human immunodeficiency virus (HIV) (Nakashima et al., 1989) and the activation of the Epstein-Barr virus early antigen (Konoshima and Kozuka, 1991). Recent in vitro studies suggest that saponin B and E have hypocholesterolemic, immuno-stimulatory, anticarcinogenic, antioxidative, antitumour, anti-virus, anti-hepatitic, anti-diabetic, and hepatoprotective effects (Fournier et al., 1998). Proc. XXVI IHC – Future for Medicinal and Aromatic Plants Eds. L.E. Craker et al. Acta Hort. 629, ISHS 2004 Publication supported by Can. Int. Dev. Agency (CIDA) 140 Six kinds of group A saponins, designated as Aa, Ab, Ac, Ad, Ae, and Af have been identified (Shiraiwa et al., 1991). The oligosaccharide chain attached to the C-22 position of the soyasapogenol A is acetylated. Acid hydrolysis of all six saponin A compounds has yielded the common aglycone, soyasapogenol A (Shiraiwa et al., 1991). The other soyasaponins, which have been isolated (designated as I, II, III, and IV) all contain soyasapogenol B as the common aglycone (Ireland and Dziedzic, 1987). It has been suggested that soyasapogenol C and E are formed as artifacts during acid hydrolysis (Ireland and Dziedzic, 1987). In contrast, Tsukamoto et al. (1993) recognized that soyasapogenol E is the aglycone of the third type of saponin, namely saponins Bd and Be. However, Bd and Be saponins are heat labile (Kudou et al., 1992), thus are presumed to be transformed into soyasapogenol B during acid hydrolysis. The total soyasaponin content is approximately twice the total soyasapogenol content (Duhan et al., 2001). The objective of this study was to develop a rapid analytical technique to isolate soyasapogenol A and B (Fig. 1) and to estimate total saponin content of soybeans. MATERIALS AND METHODS Analysis of Soyasapogenols A and B The isolation of saponins from soybean was accomplished by a modification of the method described by Daveby et al. (1998). Finely ground soybean powder (0.2 g) was dissolved in 30 mL of 80 % ethanol in a round-bottom flask with consistent mixing by a horizontal shaker for 3 h at 50 °C. The residue was removed by centrifuging the extract at 2,000 rpm for 10 min and decanting the clear supernatant. Half (15 mL) of the supernatant was dried under reduced pressure, and the residue was dissolved in 8 % HCl in anhydrous methanol and was subjected to acid hydrolysis at 75 °C for 3 h to release the aglycones (soyasapogenols) from saponins. The soyasaponogels produced were isolated by solid-phase extraction using a C18 cartridge. They were then eluted with 100 % methanol, filtered using 0.2 micron nylon filters. The quantification of soyasapogenol A and B was carried out using reverse-phase high performance liquid chromatography (RPHPLC) with external standards. The two soyasapogenols were well resolved using an ODS C18 (250 × 4.6 mm internal diameter) column at a flow rate of 0.9 mL/min with a mobile phase consisting of acetonitrile:1-propanol:water:0.1 % acetic acid whose proportions were 80:6:13.9:0.1, respectively. Owing to a lack of chromophores for these analytes, detection by UV spectrophotometry was inefficient. Evaporative light scattering detection (ELSD) was much more successfully employed to characterize and quantitate soyasapogenol A and B with very high resolution and high sensitivity. Comparison of Seed Parts and Soybean Cultivars Twenty grams of samples (replicates) of seeds were soaked in distilled water for 10 hours with aeration before separating the axis, seed coat, and cotyledons. The seed parts were freeze-dried and were ground into a fine powder. Ten food-grade soybean varieties (S20-F8, CL970321, 7025308, 9910, 2004, AC X790P, Harovinton, AC Vin-Pro, AC Hime, and 9305) were selected and were grown at four locations (Chatham, Malden, Tilbury, and Woodslee) in Ontario, Canada during 1999. RESULTS AND DISCUSSION The primary goal of the research was to develop analytical technique to determine the two major saponin components in soybeans; one (soyasapogenol A) contribute to the adverse sensory characteristics and other (soyasapogenol B) produces saponins with health benefits. In literature, quantification of saponin precursors (soyasapogenols) was contradictory because of the formation of artifacts (soyasapogenols C, D and F) during the acid hydrolysis. As well, commonly used UV-detection at 204nm is inefficient due to the lack of chromophores for soyasapogenols. As well, methods to quantify total saponins are limited due to the complexity of available procedures. The present method is developed and validated to avoid the above constraints and to quantify soyasapogenols

An efficient analytical method utilizing high-performance liquid chromatography (HPLC)/evaporative light scattering detector (ELSD) was developed to isolate and quantify the two major soyasaponin aglycones or precursors in soybeans, triterpene soyasapogenol A and B. Soaking of seeds in water up to 15 h did not change the content of soyasapogenols. Seed germination had no influence on soyasapogenol A content but increased the accumulation of soyasapogenol B. Soyasapogenols were mainly concentrated in the axis of the seeds as compared with the cotyledons and seed coat. In the seedling, the root (radicle) contained the highest concentration of soyasapogenol A, while the plumule had the greatest amounts of soyasapogenol B. In 10 advanced food-grade soybean cultivars grown in four locations in Ontario, total soyasapogenol content in soybeans was 2 +/- 0.3 mg/g. Soyasapogenol B content (1.5 +/- 0.27 mg/g) was 2.5-4.5-fold higher than soyasapogenol A content (0.49 +/- 0.1 mg/g). A significant variation in soyasapogenol content was observed among cultivars and growing locations. There was no significant correlation between the content of soyasapogenols and the total isoflavone aglycones.

The simple sequence repeat (SSR) or microsatellite marker is currently the preferred molecular marker due to its highly desirable properties. The aim of this study was to develop and characterize more SSR markers because the number of SSR markers currently available in tomato is very limited. Five hundred DNA sequences of tomato were searched for SSRs and analyzed for the design of PCR primers. Of the 158 pairs of SSR primers screened against a set of 19 diverse tomato cultivars, 129 pairs produced the expected DNA fragments in their PCR products, and 65 of them were polymorphic with the polymorphism information content (PIC) ranging from 0.09 to 0.67. Among the polymorphic loci, 2-6 SSR alleles were detected for each locus with an average of 2.7 alleles per locus; 49.2% of these loci had two alleles and 33.8% had three alleles. The vast majority (93.8%) of the microsatellite loci contained di- or tri-nucleotide repeats and only 6.2% had tetra- and penta-nucleotide repeats. It was also found that TA/AT was the most frequent type of repeat, and the polymorphism information content (PIC) was positively correlated with the number of repeats. The set of 19 tomato cultivars were clustered based on the banding patterns generated by the 65 polymorphic SSR loci. Since the markers developed in this study are primarily from expressed sequences, they can be used not only for molecular mapping, cultivar identification and marker-assisted selection, but for identifying gene-trait relations in tomato.

Isoflavones present in soybean (Glycine max) have been credited with performing several health-promoting functions, such as, prevention of cardiovascular diseases, cancers, and menopausal symptoms. In this study, the effect of the processing of soybean on the total content of isoflavones (including aglycones and glucosides) and the relative concentrations of 12 isoflavone compounds during the preparation of soy beverage and tofu were investigated. The mean recoveries of isoflavones in soy beverage and tofu in relation to their initial concentration in the raw soybeans were 54 and 36%, respectively. The estimated percentage of total isoflavones lost in the water used to soak raw soybeans, the okara (waste from heat-treated slurry), and whey were 4, 31, and 18%, respectively. The isoflavone profile of raw soybeans was altered as a result of processing. During processing, the detectable levels of aglycones, glucosides, and acetyl glycoside groups increased, whilst the corresponding malonyl glucosides decreased. The loss of isoflavones through the by-products, such as, okara and whey, was considerable. Appropriate techniques should be developed to recover and utilize these functional constituents from soybean by-products. In addition, processing techniques have to be optimized, so that the final products contain the nutrient and nutraceutical content of the starting material as much as possible.

Soymilk was made from 10 soybean [Glycine max (L.) Merr.] lines grown at three locations for 2 years, using an 18:1 water/soy protein ratio. Tofu was made with either glucono-delta-lactone (GDL) or calcium sulphate dihydrate (CS). Genotype and year effects were substantially greater than location effects on soybean protein content and seed composition; soymilk and tofu yield, solids levels, and pH; and tofu colour, hardness, and firmness. Genotype by location and genotype by year interaction effects were minor relative to the genotype and year effects. Yield of soymilk, GDL tofu, and CS tofu, which averaged 7.39 l, 6.29 kg, and 6.15 kg per kg soybeans, respectively, were all positively correlated with seed protein and stachyose, and negatively correlated with seed oil, free sugar, sucrose and remainder content. Seed protein was positively correlated with tofu hardness and firmness, while seed oil, free sugar, sucrose, and remainder content were generally negatively correlated with tofu quality parameters. Results of stepwise regression analysis showed that seed protein was the major determinant of soymilk yield and solids content, while soymilk yield was, in turn, the major factor determining GDL tofu yield. Procedures used in making soymilk and tofu play a major role in determining which seed component has a major effect on soymilk and tofu yield and quality.

A method for preparing soymilk and tofu has been developed to be used in assessing the suitability of new soybean varieties for soyfood production; the coagulants were glucono-delta-lactone and CaSO4·2H2O. The method was tested in two separate laboratories using four soybean varieties developed in Canada, three were food grade and the fourth was an oilseed variety. The soymilk and tofu pH was similar regardless of variety or lab. For soymilks yield and total solids there were significant differences (P⩽0.01) detected among varieties and between laboratories. For tofu yield and total solids the variety effects were significant in both locations (laboratories). Although reproducibility was very good within each laboratory, for each treatment there was some lack of reproducibility across laboratories. The method is best suited for use in comparative studies using a base standard as reference and is a good tool for assessing the quality of new soybean varieties for food use.

The possibility of using random amplified polymorphic DNA (RAPD) markers previously mapped in the common bean PC50/XANI59 population to select for resistance to common bacterial blight (CBB) in different populations was examined. Two out of 02 selected RAPD markers were polymorphic in HR56 and W0633d, the parental lines used in this experiment. Cosegregation analysis of the two polymorphic markers and disease reaction in a recombinant inbred (RI) population derived from HR67/W1744d confirmed that one of the two RAPD markers, BC420900, was significantly associated with a major quantitative trait locus-conditioning resistance to CBB in HR67. This locus accounted for approximately 51) of the phenotypic variation. The RAPD marker was transformed into a sequence characterized amplified region (SCAR) marker and used for selection in a different population derived from ‘Envoy’/HR67. Prediction for resistance to CBB with the BC420.990 SCAR marker was 94.2% accurate in this population. A comparison between marker-assisted selection (MAS) and conventional greenhouse screening showed that the cost of MAS is about one-third less than that of the greenhouse test.

Microsatellites or simple sequence repeats (SSRs) have been demonstrated to be abundant and hypervariable in some eukaryotic genomes. Although the presence of microsatellites is very well documented in many plant species, no information on microsatellites in beans (Phaseolus andVigna) is available. To assess the abundance and usefulness of bean microsatellites as genetic markers, 326 DNA sequences from the GenBank databases were searched. Sixty-one simple repetitive DNA sequences with 23 different types of repetitive DNA motifs were identified as potential microsatellites. Among these were 49 microsatellites from common bean (Phaseolus vulgaris) entries and 12 microsatellites from the genus Vigna. The most abundant type of microsatellite found in this search was that with di-nucleotide repeats of AT/TA. Microsatellites with tri- and tetra-nucleotide motifs were also identified. PCR analysis of 12 of the microsatellite-containing loci revealed that 11 of the 12 primer pairs could produce easily-scorable fragments, or groups of fragments. Allelic variation of the 11 loci was surveyed in 12 common bean inbred lines representing a diversity of germplasms. Seven of the 11 microsatellite loci were polymorphic and yielded 2-10 alleles. Analyses of the polymorphic loci in a common bean F6 recombinant inbred population showed that each segregated in a Mendelian fashion.Key words: microsatellite, simple sequence repeat, molecular marker, bean.

Background Genetic resistance is the most effective and sustainable approach to the control of plant pathogens that are a major constraint to agriculture worldwide. In soybean, three dominant R genes, i.e., Rsv1, Rsv3 and Rsv4, have been identified and deployed against Soybean mosaic virus (SMV) with strain-specificities. Molecular identification of virulent determinants of SMV on these resistance genes will provide essential information for the proper utilization of these resistance genes to protect soybean against SMV, and advance knowledge of virus-host interactions in general. Methodology/Principal Findings To study the gain and loss of SMV virulence on all the three resistance loci, SMV strains G7 and two G2 isolates L and LRB were used as parental viruses. SMV chimeras and mutants were created by partial genome swapping and point mutagenesis and then assessed for virulence on soybean cultivars PI96983 (Rsv1), L-29 (Rsv3), V94-5152 (Rsv4) and Williams 82 (rsv). It was found that P3 played an essential role in virulence determination on all three resistance loci and CI was required for virulence on Rsv1- and Rsv3-genotype soybeans. In addition, essential mutations in HC-Pro were also required for the gain of virulence on Rsv1-genotype soybean. To our best knowledge, this is the first report that CI and P3 are involved in virulence on Rsv1- and Rsv3-mediated resistance, respectively. Conclusions/Significance Multiple viral proteins, i.e., HC-Pro, P3 and CI, are involved in virulence on the three resistance loci and simultaneous mutations at essential positions of different viral proteins are required for an avirulent SMV strain to gain virulence on all three resistance loci. The likelihood of such mutations occurring naturally and concurrently on multiple viral proteins is low. Thus, incorporation of all three resistance genes in a soybean cultivar through gene pyramiding may provide durable resistance to SMV.

Two partial amphiploid lines, B113 (32 plants) and B21 (13 plants), derived from a wheat-Psathyrostachys huashanica intergeneric cross were characterized by Giemsa C-banding and SDS-PAGE and evaluated for stripe rust resistance. All 15 partial amphiploid plants were aneuploids with either 50 (8 plants), 51 (6 plants) or 54 (1 plant) chromosomes. Some showed regular meiosis and all the P. huashanica chromosomes were included, although not in a single plant. Of 45 plants 34 showed specific bands on SDS-PAGE representing high molecular weight glutenin subunit (HMW-GS) and 41 had bands representing P. huashanica low molecular weight glutenin subunit (LMW-GS), including two new subunits. All 45 plants were highly resistant (10) or immune (35) to stripe rust mixed races CYR-30, CYR-31, Shuiyuan 7 and Shuiyuan 14. These amphiploid plants could be useful germplasm for enhancing stripe rust resistance and might improve wheat grain quality.

Two Soybean mosaic virus (SMV) G2 isolates, L and L-RB, sharing high-sequence similarly but differing in ability to break Rsv4-mediated resistance in soybean, were investigated. Infectious clones corresponding to these two isolates and their chimeric clones resulting from swapping different regions of genomic cDNA between L and L-RB were constructed. Only L-RB or chimeras containing the middle fragment of L-RB cDNA showed virulence on Rsv4–genotype soybean. Sequence comparison analysis revealed that the middle genomic region of L and L-RB encodes four different amino acids. Point mutagenesis demonstrated that a single amino acid substitution (Q1033K) in the P3 protein determined virulence toward Rsv4 resistance. In addition, six new SMV Rsv4 resistance-breaking isolates, variants of the second passage on Williams 82 infected with the chimeras or mutants noninfectious on soybean carrying Rsv4, were obtained. Sequencing data indicated that these new isolates contain either the Q1033K mutation or a new substitution (G1054R) in P3. Site-directed mutagenesis confirmed the virulence role of the G1054R mutation on Rsv4-genotype soybean. Taken together, these data suggest that P3 of the SMV G2 strain is an avirulent determinant for Rsv4 and one single nucleotide mutation in P3 may be sufficient to compromise its elicitor function.

The poor stability and off-flavors of soybean oil and protein products can be reduced by eliminating lipoxygenases from soybean seed. Mature seeds of OX948, a lipoxygenase triple null mutant line, do not contain lipoxygenase proteins. The objective of this study was to determine the molecular basis of the seed lipoxygenase null traits in OX948. Comparisons of the sequences for lipoxygenase 1 (Lx1) and lipoxygenase 2 (Lx2) genes in the mutant (OX948) with those in a line with normal lipoxygenase levels (RG10) showed that the mutations in these genes affected a highly conserved group of six histidines necessary for enzymatic activity. The OX948 mutation in Lx1 is a 74 bp deletion in exon 8, which introduces a stop codon that prematurely terminates translation. A single T–A substitution in Lx2 changes histidine H532 (one of the iron-binding ligands essential for L-2 activity) to glutamine. The mutation in the lipoxygenase 3 (Lx3) gene in OX948 is in the promoter region and represents two single base substitutions in a cis-acting AAATAC paired box. All three mutations would result in the loss of lipoxygenase activity in mature seed. The seed lipoxygenase gene mutation-based molecular markers could be used to accelerate and simplify breeding efforts for soybean cultivars with improved flavor.

Harovinton, a variety of tofu type soybean, and 11 derived null soybean genotypes lacking specific glycinin (11S) and beta-conglycinin (7S) protein subunits were investigated to determine whether changes in protein composition affected the protein recovery in soymilk and its soluble fractions after various centrifugation steps. As both heating and homogenization have a marked effect on the increase in protein solubility, the changes occurring during these processing steps were studied for each soybean genotype. Harovinton and 11S-null genotypes showed significantly higher protein yields than the other genotypes evaluated. Subunits of group I (A(1), A(2)) of glycinin had a negative impact on protein solubility in all treatments, but this effect was the greatest in unheated soymilk samples. Samples containing a high beta-conglycinin to glycinin ratio showed an effect of heating on the solubility of the protein, as beta-conglycinin subunits aggregate with heating. The presence of the alpha' subunit of beta-conglycinin aids in the recovery of protein in the supernatant prepared from lines containing group I (A(1,4) A(2)) glycinin. The results of this study will help determine which specific protein composition will confer an increased stability in soymilk and soymilk-derived products.

A naturally occurring Rsv4 resistance-breaking isolate (L-RB) and a closely related non-resistance-breaking isolate (L) of Soybean mosaic virus (SMV) were identified in soybean fields in London, Ontario, Canada. The viral genomes of L and L-RB were completely sequenced. Each isolate has a 9585-nucleotide genome with a single open reading frame encoding a polyprotein of approximately 350 kDa. L-RB and L have a very high sequence similarity (99.6%) at both the nucleotide and amino acid levels. Phylogenetic analysis showed that the two isolates belong to the G2 pathotype. Pathogenicity predictions of all virus/soybean combinations, based on the phylogenetic profile, were confirmed by pathogenicity tests using L and L-RB isolates and soybeans carrying different resistance genes, with an exception that L-RB infected a soybean cultivar carrying Rsv4 resistance. The temporal and spatial proximity of L and L-RB and their high sequence similarity suggest L-RB was likely derived from the SMV-L quasispecies. Recombination analysis did not reveal the evidence of genetic recombination for the emergence of L-RB. Mutations introduced by virus-encoded RNA-dependent RNA polymerase during viral genome replication and selection pressure probably contributed to the occurrence of L-RB.

Linolenic acid and seed lipoxygenases are associated with off flavours in soybean products. F5recombinant inbred lines (RILs) from a cross between a low linolenic acid line (RG10) and a seed lipoxygenase-free line (OX948) were genotyped for simple sequence repeats (SSR), random amplified polymorphic DNA (RAPD), sequence-tagged sites (STS), and cleaved amplified polymorphic sequence (CAPS) markers and evaluated for seed and agronomic traits at 3 Ontario locations in 2 years. One hundred twenty markers covering 1247.5 cM were mapped to 18 linkage groups (LGs) in the soybean composite genetic map. Seed lipoxygenases L-1 and L-2 mapped as single major genes to the same location on LG G13-F. L-3 mapped to LG G11-E. This is the first report of a map position for L-3. A major quantitative trait locus (QTL) associated with reduced linolenic acid content was identified on LG G3-B2. QTLs for 12 additional seed and agronomic traits were detected. Linolenic acid content, linoleic acid content, yield, seed mass, protein content, and plant height QTL were present in at least 4 of 6 environments. Three to 8 QTLs per trait were detected that accounted for up to 78% of total variation. Linolenic acid and lipoxygenase loci did not overlap yield QTL, suggesting that it should be possible to develop high-yielding lines resistant to oxidative degradation by marker-assisted selection (MAS).

Functional properties of soy proteins for food are closely related to the composition of their storage protein subunits. Using base excision sequence scanning (BESS), we show that the absence of the A4 peptide in the G4 glycinin subunit of the soybean (Glycine max L.) cultivar Enrei was caused by the same point mutation in the Gy4 gene as previously reported in the soybean cultivar Raiden. Although the genetic relationship between Raiden and Enrei is not known, the same point mutation in their Gy4 genes may indicate that they probably share a related origin. The application of BESS to identify single nucleotide polymorphisms (SNPs) as co-dominant markers for marker-assisted selection (MAS) of a recessive null allele is also discussed.

Soybean (Glycine max (L.) Merr.) seeds vary in their surface properties. The lustre, or glossiness, of seeds has been classified into several different phenotypes. Soybean seeds that have a dull lustre or moderate bloom (B) may also have abundant seed surface protein, namely, an abundance of the hydrophobic protein from soybean (HPS). The seed surface protein HPS is an allergen (Gly m 1) that causes asthma in persons allergic to soybean dust. In this study, seed lustre and surface protein content are compared among 71 different soybean cultivars and lines. Dull-seeded phenotypes usually possessed abundant surface protein in comparison to shiny-seeded types, although exceptions were observed. An F2population of 82 individuals from a cross of OX281 (dull lustre, abundant HPS) and Mukden (shiny lustre, trace amounts of HPS) provided a basis for inheritance studies and genetic mapping analysis. Results indicate that dull seed lustre (B) and surface protein (Hps) loci are dominant Mendelian traits that cosegregate and map to soybean linkage group E. Molecular markers were used to construct a genetic map of 28 cM encompassing B and Hps. Two different molecular markers cosegregated with each of the loci. This study provides additional evidence that Hps may play a role in the adhesion of endocarp tissues to the seed, and offers new methods of selection for seed lustre and surface protein composition in soybean.Key words: adhesion, allergen, hydrophobic protein, pericarp, seed coat.

Dietary intake of isoflavones has been shown to reduce the risk of several major diseases in humans. Therefore, breeding soybean [Glycine max (L.) Merrill] seeds with desirable isoflavone content would be beneficial to the food and health industries, but the environmental sensitivity of the trait complicates phenotypic selection. The objective of this study was to identify quantitative trait loci (QTL) and epistatic interactions associated with isoflavone contents in soybean seeds. A population of 207 F 4:6 recombinant inbred lines (RILs) was produced from the cross 'AC756' × 'RCAT Angora'. The population was phenotyped at two locations in Ontario, Canada, and genotyped by means of 99 polymorphic SSR markers. A significant genotype X environment interaction was found. Seventeen QTLs were detected (P < 0.01) by single-factor ANOVA. Individual loci explained up to 10.5% (P < 0.0001) of the phenotypic variation. Interval mapping and composite interval mapping identified nine genomic regions (LGs Al, C2, D1a, F, G, H, J, K, and M) associated with isoflavone contents. Some QTL associated with agronomic or seed quality traits mapped to the same regions as those for individual isoflavone contents on LGs Al, C2, F, J, K, M, and N. Twenty-three epistatic interactions were detected for isoflavones. Multiple locus models explained up to 25.0% (P < 0.0001) of the phenotypic variation without epistasis and up to 35.8% (P < 0.0001) with it. The QTL identified in this study could be useful for developing soybean varieties with desirable isoflavone content in the seed through marker-assisted selection (MAS).