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HS-182 and HS-183 are food-grade soybean lines [Glycine max (L.) Merr.] with distinct seed protein profiles and food processing quality. HS-182 is a 7S β-conglycinin α’ and 11S glycinin A4 null with a high protein concentration of 45.7% and good processing quality. HS-183 is a 7S β-conglycinin α’ and 11S glycinin null with a protein concentration of 42.7% and poor tofu processing quality. They are adapted to areas of southwestern Ontario with 3100 or more crop heat units and have relative maturity groups of 2.5 and 2.4, respectively.

AAC Big Ben is a high yielding, soybean cyst nematode resistant food-grade soybean [Glycine max (L.) Merr.] cultivar with yellow hilum and acceptable processing quality for foreign and domestic tofu, soymilk, and miso markets. AAC Big Ben was developed at the Agriculture and Agri-Food Canada (AAFC) Harrow Research and Development Centre (Harrow-RDC), Harrow, ON. AAC Big Ben is adapted to areas of southwestern Ontario with 3300 or more crop heat units and has a relative maturity group of 2.3 (MG 2.3).

AAC Wigle is a high yielding, high-protein, large-seeded, soybean cyst nematode resistant food-grade soybean [Glycine max (L.) Merr.] cultivar with yellow hilum and acceptable processing quality for foreign and domestic tofu, soymilk, and miso markets. It was developed at the Agriculture and Agri-Food Canada (AAFC) Harrow Research and Development Centre (Harrow-RDC), Harrow, ON. AAC Wigle is adapted to areas of southwestern Ontario with 3200 or more crop heat units and has a relative maturity of 2.2 (MG 2.2) and protein content of 45.8%.

Soybean (Glycine max [L.] Merr.) is a major isoflavone producing legume. Isoflavones and their derivatives function as phytoalexins that may function in protecting plants against pathogens. They are also known as phytoestrogens in the human diet, which have putative positive human health effects such as reduced risk of breast and prostate cancers, cardiovascular disease, and high blood cholesterol levels. Therefore, increasing isoflavone concentration could be a desirable target for developing added value for food-grade soybean cultivars. Soybean cyst nematode (SCN; Heterodera glycines) is the most yield-limiting pathogen for soybean world-wide. The objectives of this study were to: 1) determine genotype (G) and genotype-by-environment (GE) interaction variation for seed isoflavone concentration and, 2) determine the effects that SCN resistance may have on seed isoflavone concentration in SCN infested and non-infested environments. A population of 109 recombinant inbred lines (RILs), derived from a cross between DH4202 and RCAT1004, along with 11 commercial check cultivars were grown in two SCN infested and two non-infested fields in southern Ontario, Canada, in 2015 and 2016. The genotypes were categorized into resistant, moderately resistant, and susceptible lines based on SCN female indices calculated from SCN infested environments. Significant G, environment (E), and GE interaction effects were observed for total isoflavone concentration as well as for yield. Higher isoflavone concentrations were observed in non-infested environments when compared with SCN infested environments for all three levels of resistance. Within SCN infested environments, resistant genotypes had significantly higher isoflavone concentrations than susceptible genotypes, indicating a potential role of isoflavones in plant defense from SCN in resistant genotypes. SCN infested environments were found to be more reliable for genotype evaluation of isoflavone concentration than non-infested environments due to similar relative performance of genotypes in all SCN infested environments. A strong relationship between the level of SCN resistance and relative yield among the genotypes was observed in SCN environments. When evaluating genotypes, soybean breeders should consider the negative impact SCN has on seed isoflavone concentration, the positive relationship between SCN resistance and isoflavone concentration in SCN environments, as well as the greater stability in isoflavone concentration across genotypes within SCN environments compared to the non-infested ones.

HS-181 is an 11S glycinin null food-grade soybean line [Glycine max (L.) Merr.] with yellow hilum. The absence of 11S subunits would result in a relatively higher concentration of 7S β-conglycinin in soy food. β-conglycinins suppress food intake, which can help to fight obesity. HS-181 is adapted to areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity of 2.5 (MG 2.5).

Four soybean storage protein subunit QTLs were mapped using bulked segregant analysis and an F2 population, which were validated with an F5 RIL population. The storage protein globulins β-conglycinin (7S subunit) and glycinin (11S subunits) can affect the quantity and quality of proteins found in soybean seeds and account for more than 70% of the total soybean protein. Manipulating the storage protein subunits to enhance soymeal nutrition and for desirable tofu manufacturing characteristics are two end-use quality goals in soybean breeding programs. To aid in developing soybean cultivars with desired seed composition, an F2 mapping population (n = 448) and an F5 RIL population (n = 180) were developed by crossing high protein cultivar ‘Harovinton’ with the breeding line SQ97-0263_3-1a, which lacks the 7S α′, 11S A1, 11S A2, 11S A3 and 11S A4 subunits. The storage protein composition of each individual in the F2 and F5 populations were profiled using SDS-PAGE. Based on the presence/absence of the subunits, genomic DNA bulks were formed among the F2 plants to identify genomic regions controlling the 7S α′ and 11S protein subunits. By utilizing polymorphic SNPs between the bulks characterized with Illumina SoySNP50K iSelect BeadChips at targeted genomic regions, KASP assays were designed and used to map QTLs causing the loss of the subunits. Soybean storage protein QTLs were identified on Chromosome 3 (11S A1), Chromosome 10 (7S α′ and 11S A4), and Chromosome 13 (11S A3), which were also validated in the F5 RIL population. The results of this research could allow for the deployment of marker-assisted selection for desired storage protein subunits by screening breeding populations using the SNPs linked with the subunits of interest.

HS-172 is a black-seeded food-grade soybean line [Glycine max (L.) Merr.] suitable for use to make douchi or fermented, salt-preserved black soybean. It is adapted to the areas of southwest Ontario with 3100 or more crop heat units and has a relative maturity rating of 2.5.

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.

To select dry bean ( Phaseolus vulgaris L.) vari- eties suitable for the canning and processing industry, it is essential to understand the genetic and environmental effects on the quality param - eters as well as their associations. A dataset of 6 yr of dry bean quality evaluations in the multi- location provincial registration trials in o ntario, Canada, with data for parameters routinely used by breeding programs to predict the final can ning quality of breeding materials was used. Genetic, environmental, and genotype (G) × environmental effects and multi-variable asso - ciations were studied using the estimates of the genotypic least squared means for the balanced yearly data and the best linear unbiased predic - tors (BLUps) for the overall unbalanced data. Genetic effects, accounting for 35 to 76% of the variation in navy bean and 38 to 88% of the vari - ation in large-seeded bean, followed by location (L) effects, accounting for 11 to 66% of the varia - tion in navy bean and 11 to 64% of the variation in large-seeded bean, were more important than the genotypelocation (GL) interaction effects for seed composition parameters. This was not the case for physical and texture parameters, where GL interaction effects were often most important. p associations were observed among hydration coefficient, can yield, and pro - tein content in the yearly analyses as well as in the multi-year analysis. The negative association between percent washed-drain solids and bean texture after processing was also repeatedly observed over years. The associations reported here may guide further selection efforts in bean breeding programs.

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.

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.

Future soybean [Glycine max (L.) Merr.] cultivars with elevated or reduced concentrations of isoflavones may be required to satisfy the food market. Climate influences isoflavone concentration making their prediction problematic. Our research examined the associations between precipitation and temperature during a growing season with the isoflavone concentration in the harvested seed. We grew 14 cultivars across 12 years, at one location and calculated climate parameters for readily identifiable growth stage intervals (GSI). We correlated the climate parameters within each GSI with seed daidzein, genistein and total isoflavone (TIF) concentrations. We found that cumulative precipitation from the mid-vegetative to the flowering period was correlated with daidzein and TIF concentration. Mean daily average T during early vegetative development was positively correlated with daidzein and TIF concentration and this was largely a result of higher minimum daily T. Accumulated heat stress T greater than 27 °C during seed development was significantly correlated with a reduction in genistein and TIF, but not daidzein concentration. Accumulated cold stress T's less than 20, 15 and 17 °C during seedling emergence were significantly correlated with higher seed daidzein, genistein and TIF concentrations, respectively in all short-season cultivars tested. Cold stress T during seedling emergence could be used to predict seasonal changes in isoflavone concentrations.

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.

Isoflavones are naturally occurring compounds found in soybean [Glycine max (L.) Merr.]. Soybean isoflavone, as a quantitative trait, is subject to significant genotype x environment interaction, which makes breeding for this trait difficult. Thirty F 4:7 soybean lines, derived from crosses of 'RCAT Angora' x CK-01 and 'Heinong 35' x 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 x environment (G x E) interaction were significant. Consistently performing genotypes from the two populations were identified by several stability parameters. Genotype-genotype x 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.

Soybean, Glycine max (L.) Merr., seeds contain isoflavones, compounds with potential human health benefits. This study investigated the association of seed and agronomic traits with isoflavone level in a genetically diverse group of soybean genotypes to provide more information for cultivar development. F4:7 lines derived from several crosses were grown in four locations in 2005 and six locations in 2006 across Ontario and Quebec. Seed protein, oil and isoflavone contents were measured using near-infrared reflectance (NIR) on a plot basis. Seed yield was determined at 13% moisture and days to maturity (R8) were recorded. GGE genotype-by-trait biplots were generated to describe the relationships among all variables. Isoflavone content was not correlated with yield, indicating that potential exists for development of high or low isoflavone cultivars without sacrificing yield. Isoflavone content was negatively correlated with protein content; however, high isoflavone lines were identified with moderate protein content. Isoflavone content was correlated with maturity, suggesting that delayed planting and/or the use of later maturing varieties could be a successful strategy to increase isoflavone content. The results of this study support the potential for the development of either high or low isoflavone soybean cultivars with acceptable agronomic and seed quality traits.Key words: Soybean, isoflavone, protein, oil, yield, maturity

Soybean [Glycine max (L.) Merr.] seeds contain a high concentration of the isoflavones daidzein and genistein, which are considered to be compounds beneficial to human health. Our objective was to determine the influence of breeding and selection for yield on the isoflavone concentration of short-season cultivars. A collection of 14 historical cultivars released from 1934 to 1992 was grown at Ottawa for 12 yr under identical cultural conditions. Seed samples, taken at harvest, were examined using near-infrared reflectance in conjunction with traditional chemical methods to measure the concentration of daidzein, genistein, and total isoflavones (TIF). A linear regression equation developed based on the changes across time of cultivar release was used to determine the improvement rates for various soybean parameters. Across the 58 yr of breeding history, yield and oil concentration increased by 0.43 and 0.24% per year, respectively, while protein concentration decreased by 0.15% per year. Across the same time period daidzein, genistein, and TIF increased by 1.04, 1.47, and 0.98% per year, respectively. Moderate broad sense heritabilities of 43, 45, and 44% were calculated for the aforementioned isoflavones. Genotype main effects + genotype x environment interaction biplots revealed that recent cultivars with high isoflavone concentration were more prone to environmental influence than older cultivars. In the short-season region, plant breeders should be aware that selecting for higher yield may indirectly select for higher isoflavone concentration.

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.

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.

1. This study evaluated the effect of dispersal on the density and feeding impact of a phytophagous insect in relation to the spatial distribution of its host plants. 2. The interaction between density, dispersal, and feeding impact of western flower thrips on flowering chrysanthemum was quantified at three spatial scales, with infested and uninfested plants either isolated in 0.25 m2 individual cages, or enclosed together in 2.25 m2 communal cages or 75 m2 greenhouses. 3. In individual cages, the rate of dispersal from chrysanthemum plants to blue sticky traps increased with the density of thrips for females but not males. Uninfested plants consistently had fewer thrips when they were individually caged rather than enclosed with plants infested with adults, indicating that dispersal mediates inter-plant distribution of thrips. 4. The feeding impact of thrips on inflorescences was evaluated using the absorbance of ethanol extracts at wavelengths characteristic of yellow carotenoid pigments associated with chrysanthemum inflorescences (415, 445, and 472 nm). Increasing absorbance of extracts with increasing density of thrips per inflorescence suggests that feeding by thrips results in ruptured cells leaching carotenoid pigments. 5. In communal cages, the distribution of thrips was uniform for infested and uninfested plants, whereas the density and feeding impact of thrips in greenhouses were higher for infested than uninfested plants. These results suggest that short-range dispersal by adults homogenises the density and feeding impact of thrips among host plants only on a small spatial scale.

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.

When higher plants are exposed to elevated levels of CO2 for both short- and long-term periods photosynthetic C-gain and photoassimilate export from leaves are generally increased. Water use efficiency is increased on a leaf area basis. During long-term exposures, photosynthesis rates on leaf and whole plants bases are altered in a species specific manner. The most common pattern in C3 plants is an enhanced rate of whole plant photosynthesis in a well irradiated canopy. Nevertheless, in some herbaceous species prolonged exposure to high CO2 results in remobilization of nitrogenous reserves (i.e., leaf protein degradation) and reduced rates of mature leaf photosynthesis when assayed at ambient CO2 and O2 levels. Both short- and long-term exposures to those CO2 levels (i.e., 100 to 2,000 microliter l-1) which modify photosynthesis and export, also modify both endogenous ethylene gas (C2H4) release, and substrate, 1-aminocyclopropane-1-carboxylic acid (ACC), saturated C2H4 release rates from irradiated leaves. Photosynthetically active canopy leaves contribute most of the C2H4 released from the canopy. Prolonged growth at high CO2 results in a persistent increase in the rate of endogenous C2H4 release from leaves which can, only in part, be attributed to the increase of the endogenous pools of C2H4 pathway intermediates (e.g., methionine, M-ACC, and ACC). The capacity for increasing the rate of C2H4 release in response to short-term exposures to varying CO2 levels does not decline after prolonged growth at high CO2. When leaves, whole plants, and model canopies of tomato plants are exposed to exogenous C2H4 a reduction in the rate of photosynthesis can, in each case, be attributed to the classical effects of C2H4 on plant development and morphology. The effect of C2H4 on CO2 gas exchange of plant canopies is shown to be dependent on the canopy leaf area index.

The effects of long-term and transient exposure to elevated CO 2 concentrations on photosynthetic gas exchange and ethylene release by tomato leaves were investigated. The net CO 2 assimilation rate was enhanced when leaf tissue grown at ambient (35 Pa CO 2 ) levels was assayed at 100 Pa CO 2 . Leaf tissue grown at high (130 Pa) CO 2 exhibited a lower net CO 2 assimilation rate at high CO 2 levels than leaf tissue grown at ambient (35 Pa) CO 2 . This decrease in CO 2 exchange rate in response to growth at high CO 2 is typical of C 3 species

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.

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.

Current evidence indicates that ethylene is a volatile by-product of amino acid metabolism. Ethylene synthesis is linked with nitrogen metabolism through methionine and S-adenosylmethionine and as a volatile emission may serve as a non-destructive probe of amino acid turnover during photosynthesis and photorespiration. Very little is known about the relationship between ethylene and CO2 gas exchange in photosynthetic tissue. CO2 enhances the rate of ethylene release from leaf tissue in the light (1–5) and it has been proposed (3) that ethylene synthesis and/or metabolism may be moderated by photosynthetic and respiratory processes in photosynthetically competent leaves through changes in the internal CO2 concentrations.

Petioles of the celery-leaved buttercup, Ranunculus sceleratus L., elongate when the leaf blades are submerged. This elongation has been correlated with a rise in internal C 2 H 4 levels. Treatment with C 2 H 4 in air will also enhance petiole growth. The submergence-induced growth is inhibited in the presence of CoCl 2 solutions. Cobalt treatment does not inhibit petiole elongation when the leaves are exposed to C 2 H 4 in air or when the tissues are submerged in C 2 H 4 -saturated CoCl 2 solutions. Thus, the physiological effect of CoCl 2 is completely mitigated by treatment with C 2 H 4 . Cobalt can directly inhibit C 2 H 4 production by leaf tissue. There is no evidence of the effect being dependent on changes in CO 2 metabolism.

The effects of ethylene evolved from ethephon on leaf and whole plant photosynthesis in Xanthium strumarium L. were examined. Ethylene-induced epinasty reduced light interception by the leaves of ethephon treated plants by up to 60%. Gas exchange values of individual, attached leaves under identical assay conditions were not inhibited even after 36 hours of ethylene exposure, although treated leaves required a longer induction period to achieve steady state photosynthesis. The speed of translocation of recently fixed 11C-assimilate movement was not seriously impaired following ethephon treatment; however, a greater proportion of the assimilate was partitioned downward toward the roots. Within 24 hours of ethephon treatment, the whole plant net carbon exchange rate expressed on a per plant basis or a leaf area basis had dropped by 35%. The apparent inhibition of net carbon exchange rate was reversed by physically repositioning the leaves with respect to the light source. Ethylene exposure also inhibited expansion of young leaves which was partially reversed when the leaves were repositioned. The data indicated that ethylene indirectly affected net C gain and plant growth through modification of light interception and altered sink demand without directly inhibiting leaf photosynthesis.

Woodrow, L., Thompson, R. G. and Grodzinski, B. 1988. Effects of ethylene on photosynthesis and partitioning in tomato, Lycopersicon esculentum Mill.—J. exp. Bot. 39: 667-684. The extended period of ethylene release from ethephon (2-chloroethylphosphonic acid) after application to intact tomato plants has provided a model system in which the effects of ethylene on photosynthetic metabolism and carbon partitioning has been studied. Ethylene release from leaf tissue after ethephon treatment was 10 times greater than that from untreated control leaves. The specific activity of 14C2H4 released from [14C] ethephon remained constant over several days demonstrating that the ethylene was derived from the applied ethephon. The ethephon-treated plants exhibited extreme epinasty of the leaves and 24 h after application the flower buds in the first visible cluster had abscised, leaf expansion at the apex had ceased and developing adventitious roots were visible on the lower stem. Rates of steady-state photosynthesis, respiration, photorespiration and transpiration were the same in treated and control leaves 24 h after ethephon application. Both treated and control leaves partitioned similar proportions of newly-fixed 14C from 14C02 into neutral (46-4%), acidic (14 0%), basic (5 0%) and insoluble (34 0%) leaf fractions under steady-state conditions. The speed of 11 C-assimilate movement in the stems of control plants (3-62 ± 0-42 cm min "1 towards the apex and 403 ±015 cm min-1 towards the roots) was more rapid than in the ethephon-treated plants (2-90±0-31 cm min"1 upwards and 2-59±0-22 cm min-1 downwards). Furthermore, in the control plants 20 0 + 5-4% of the 14C exported to the plant from the source leaf was transported towards the developing flower cluster and young leaves. Twenty-four hours after ethephon application only 6-5 ± 1-7% of the exported 14C was translocated towards the shoot. Contrary to some reports ethylene did not affect steady-state gas exchange processes while carbon partitioning was significantly altered indicating that ethylene effects on photosynthetic carbon metabolism are indirect and not due to direct effects on photosynthetic processes per se. Key words— Ethylene, photosynthesis, partitioning. Correspondence to: Department of Horticultural Science, University of Guelph, Guelph, Ontario NIG 2W1, Canada.

Glycine decarboxylation and serine synthesis were studied in pea (Pisum sativum L.) leaf discs, in metabolically active intact chloroplasts, and in mitochondria isolated both partially by differential centrifugation (i.e. ;crude') and by further purification on a Percoll gradient. Glycolate, glyoxylate, and formate reduced glycine decarboxylase activity ((14)CO(2) and NH(3) release) in the crude green-colored mitochondrial fractions, and in the leaf discs without markedly altering serine synthesis from [1-(14)C]glycine. Glycolate acted because it was converted to glyoxylate which behaves as a noncompetitive inhibitor (K(i) = 5.1 +/- 0.5 millimolar) on the mitochondrial glycine decarboxylation reaction in both crude and Percoll-purified mitochondria. In contrast, formate facilitates glycine to serine conversion by a route which does not involve glycine breakdown in the crude mitochondrial fraction and leaf discs. Formate does not alter the conversion of two molecules of glycine to one CO(2), one NH(3), and one serine molecule in the Percoll-purified mitochondria. In chloroplasts which were unable to break glycine down to CO(2) and NH(3), serine was labeled equally from [(14)C]formate and [1-(14)C]glycine. The maximum rate of serine synthesis observed in chloroplasts is similar to that in isolated metabolically active mitochondria. Formate does not appear to be able to substitute for the one-carbon unit produced during mitochondrial glycine breakdown but can facilitate serine synthesis from glycine in a chloroplast reaction which is probably a secondary one in vivo.

Many external as well as internal factors control the partitioning of metabolites from source leaves to developing sinks. Initially, however all carbon in the plant and all energy used for the growth and development are derived through photosynthesis. With respect to net assimilation of CO2, photorespiration (ie. the release of CO2 in the light) is frequently viewed by breeders as an antagonistic process possibly even wasteful (1,2,3,4,5,6). However, in terms of maintaining whole plant growth in the natural environment photorespiration may have several homeostatic roles (7,8,9) which provide clear advantages to a plant facing adverse conditions. With the view to a better understanding of photorespiration and the role(s) it might preform, our studies have been focussed on the identification of the ‘end products’ of photorespiration at the cellular level and the relationship of their metabolism to the growth and development of the whole plant. As indicated in Fig. 1, the products of the glycolate pathway which actually leave the cell are CO 2, the transport sugars (primarily sucrose), and amino acids (eg. glycine, serine, glutamate, glutamine).

Ethylene gas is a normal product of plant metabolism and is considered to be an important co-regulator of many developmental processes. In higher plants ethylene biosynthesis proceeds from methionine through S-adenosylmethionine (SAM) to 1-aminocyclopropane-l-carboxylic acid (ACC) to ethylene (Yang, 1982). SAM functions as a methyl donor in many biochemical reactions in living tissue and is not restricted to the ethylene biosynthetic pathway. ACC however appears to have a unique role as the immediate precursor of ethylene. Green leaf tissue normally has a low endogenous ethylene production rate (20–200 pmoles/gm fr wt/h) and until recently studies with mature leaf tissue have been primarily concerned with leaf senescence and the role of ethylene in this process. Interest in leaf tissue has been increased by the observation that photosynthesis can play a role in ethylene metabolism (Gepstein, Thimann, 1980; de Laat et al., 1981; Grodzinski et al., 1982a,b; 1983; Horton et al., 1982). Several studies earlier suggested that light inhibits ethylene production in photosynthetically active leaf tissue when compared to rates obtained in the dark (Gepstein, Thimann, 1980; de Laat et al., 1981). However when leaf tissue is illuminated and the CO2 levels within the experimental system are maintained above the compensation point this inhibition is not apparent in either C3 or C4 plants (Grodzinski et al., 1982a,b;1983). Interestingly in the light ethylene release from Cl tissue never exceeds that in the dark even under conditions of high t02. The major inhibitory effect attributed to light is due to the depressed CO2 levels which are a result of the balance of photosynthetic and respiratory activity within the tissue (Grodzinski et al., 1982a). The difference between C3 and C4 plants may reflect the different carboxylation patterns in These two types and the relative ability to regulate internal CO2 concentrations. The amount of carbon flowing through the ethylene pathway is very small (pmoles carbon/mg Chl/h) in comparison to the flow through the major metabolic pathways (pmoles carbon/mg Chl/h). Ethylene metabolism and the resultant physiological effects may be subject to the many processes that can significantly modify the internal CO2 environment of the tissue. Ethylene release is responsive to changes in external CO2 concentration over the range extending from 0.0 to 0.10% which includes normal ambient levels (Woodrow, 1982; Woodrow and Horton, in preparation). Furthermore, a significant production of CO2 within the tissue from a photorespiratory intermediate (eg. glycolate) could represent a homeostatic mechanism by which internal CO2 pools may regulate ethylene metabolism. This would parallel the proposed role for photorespiration as a means of dissipating reducing energy under photo-oxidative conditions.

The stimulatory effect of CO2 on ethylene evolution from photosynthetically active excised and intact leaf tissue of both C3 and C4 plants is now well documented (Dhawan, Bassi, and Spencer, 1981; Fuhrer, 1983; Grodzinski, Boesel, and Horton, 1982a, b; 1983; Grodzinski, 1984; Kao and Yang, 1982; Woodrow and Grodzinski, 1987). The range of CO2 concentrations over which ethylene release is most responsive, 50 to 1500 ul L−1, coincides with those encountered by leaf tissue in sealed greenhouse environments under conditions of CO2 depletion or CO2 enrichment (Porter and Grodzinski, 1985; Woodrow and Grodzinski, 1987). Interestingly the current global CO2 levels and the predicted future elevated concentrations also fall within this range. Because the stimulation of ethylene release by elevated CO2 is direct and readily reversible (Grodzinski et al., 1982a, b; 1983) in both C3 and C4 plants we originally suggested that CO2 may stimulate the synthesis of ACC or ethylene and/or affect the retention and metabolism of ethylene (Grodzinski et al., 1982a,b). Nilsen and Hodges (1983) and Fuhrer (1985) also present data which support the concept of retention as a mechanism of the CO2 effect. Alternately Kao and Yang (1982) favour the view that the ACC to ethylene conversion step is directly affected by CO2. Incubations of leaf tissue at high CO2 concentrations have also resulted in increased ethylene-forming enzyme content (Philosoph-Hadas, Aharoni, and Yang, 1986).

Interest in CO2 enrichment has focussed primarily on its application in horticultural greenhouse production (1). CO2 may be added to the greenhouse atmosphere to maintain a level of approximately 330ul/L or enriched to higher levels (eg. 700–1500 μ1/L) to further stimulate growth. Elevated CO2 levels are also experienced by crops in some outdoor production situations. Recently Wallis and Grodzinski (2) reported that sweet pepper plants grown inside polyethylene tunnels on mulched soil experienced CO2 levels exceeding 3000 μ1/L due to soil respiration and restricted gas exchange. Potential global increases in CO2 concentration have also stimulated interest in plant responses to altered CO2 levels (3). Growth and development of plants is associated with photosynthetic activity and partitioning of carbon (4) as well as with the action and integration of plant growth regulators (5). In this study determinate tomato plants were grown as transplant stock at CO2 concentrations of 300, 1000, and 3000 μ1/L. Their growth and photosynthetic metabolism was studied during the period of early vegetative development. Leaf ethylene metabolism was examined as it relates to leaf photosynthetic activity and potential growth regulation.