Soybeans with large seed size, uniformity, clear hilum, and high 11S/7S ratio are favored for soymilk and tofu making. In order to find ideal soybean lines for food making, sixty-eight soybean lines, which were selected from thousands of accessions in the USDA-Soybean Germplasm Collection, were planted in three successive seasons. Eight lines were identified from twenty-two lines harvested in 2014 (Stoneville, MS) to be suitable for tofu making as judged by chemical composition and sensory quality of tofu. The results provided important food quality information to the growers, breeders and tofu industries for their selection of soybean to improve food quality. In the filled tofu making and texture analysis study, the correlation between A3 subunit percentage and tofu firmness was significant (N=22. r = 0.77, P < 0.001). The result proved that the percentage of A3 subunits could be an indicator for predicting the firmness of tofu.

With the increasing scarcity of water resources, soil moisture stress is the single most threat to global soybean production causing extensive yield losses. The objectives of this study were to investigate soil moisture stress effects on all aspects of soybean growth and development processes and to develop functional algorithms that could be used for field management decisions and in soybean crop modeling. To fulfill these objectives, six experiments were conducted; one in vitro osmotic stress study on seed germination, four studies by imposing five soil moisture treatments, 100, 80, 60, 40, and 20% of daily evapotranspiration of the control at different growth stages using sunlit plant growth chambers, and one transgenerational study on seed germination at different osmotic levels and offspring growth at three irrigation treatments (100, 66, and 33% based on field capacity) for plants grown at different soil moisture levels. Two cultivars from maturity group V, Asgrow AG5332 and Progeny P5333RY, with different growth habits were used in all these studies. Midday leaf water potential, plant height, mainstem nodes, gas-exchange traits, canopy reflectance, and several yield components including pod weight, seed yield, and seed quality were measured. Soil moisture stress decreased biomass, net photosynthesis, yield, individual seed weight, maximum seed germination, protein, fatty acids, sucrose, N, and P and increased oil, stachyose, Fe, Mg, Zn, Cu, and B contents. Overall, Asgrow AG5332 was more tolerant to drought stress than Progeny P5333RY. Soil moisture stress induced changes in seed quality that were correlated with seed germination and seedling vigor in the F1 generation. These data can be used to build a model-based decision support system capable of predicting yield under field conditions.

The infection of plants by Heterodera glycines, commonly known as soybean cyst nematode (SCN), is a serious agricultural problem of worldwide extent. Meanwhile, it provides an excellent experimental model to study basic aspects of how cells function, in particular, during biotic challenge. Heterodera glycines challenges plant cells by initiating, developing and sustaining an interaction that results in the formation of a nurse cell from which the nematode derives nourishment. The presented experiments examine (1) how a cell can be de-differentiated and reprogrammed to perform a much different biological role and (2) how a cell’s immune responses can be engaged or suppressed to accomplish that goal. The observation of alpha soluble N-ethylmaleimide-sensitive factor attachment protein (alpha-SNAP) expression, its location within the rhg1 locus and known involvement in the vesicular transport machinery relating to defense made it a strong candidate for further functional analysis. Functional studies demonstrated that overexpression of alpha-SNAP in the susceptible G. max[Williams 82/PI 518671] genotype that lacks its expression results in the partial suppression of H. glycines infection. This indicated that the vesicles could be delivering cargo to the site of infection to engage a defense response. High levels of expression of a cell wall modifying gene called xyloglucan endotransglycosylase also occur during defense. XTHs associate with vesicles, act in the apoplast outside of the cell, and have a well-known function in cell wall restructuring. These observations indicated that alterations in the cell wall composition of nurse cells could be important for the successful defense response. Overexpression of a G. max xyloglucan endotransglycosylase (Gm-XTH) in the susceptible G. max[Williams 82/PI 518671] genotype resulted in a significant negative effect on H. glycines as well as R. reniformis parasitism. The results, including preliminary experiments on components of the vesicle transport system, identify a potent mechanism employed by plants to defend themselves from two types of plant-parasitic nematodes.

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Strain-specific resistance conditioned by a single dominant gene in soybean cv. York inoculated with SMV-G1, revealed no symptoms and no detectable viral replication (R). Unlike the hypersensitive response (HR), the R response did not result in localized virus and induction of a series of defense responses, but in inhibition of virus replication. However, this resistance was overcome by the resistance- breaking strain, SMV-G4, which induced lethal necrosis (N). Unlike HR, G4 strain was not restricted but spread ina restricted pattern along the vein, stem and into upper un-inoculated leaves where it induced necrosis. Like HR, PR proteins were found to accumulate in the N response and were named SPR (soybean pathogenesis-related) proteins. On the basis of major similarities in molecular weight characteristics and enzyme-substrate specificities, SPRs are proposed to be classed into four groups: SPR1; 1a, 1b, 1c, 1d; SPR2: 2a, 2b, 2c; SPR3: 3a, 3a’, 3b, 3c, 3d, 3e; SPR4. The functions of SPR1 and SPR4 groups have not yet been determined. The SPR2 group was identified as β-1,3-glucanases (GLN) and classed two subgroups. The SPR3 group was identified as chitinases (CHN) and classed three distinct subgroups. Like HR, the N response induced a series of defense responses with marked temporal increases, in a bimodal pattern, of phenylalanine ammonia-lyase (PAL) and peroxidase (POX) activities, bimodal pattern of PAL mRNA and chalcone synthase (CHS) mRNA induction, a single pattern of chitinase mRNA induction, and glyceollin and lignin accumulation. These marked increases occurred at or just before the time of initial appearance of necrotic lesions, or following necrosis development for localization of virus. Total RNA isolated from soybean inoculated with SMV-G4 were used for synthesis of cDNA by reverse transcription, and amplified using 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGR)-specific primer sets by polymerase chain reaction. Amplified cDNAs were cloned into Bluescript vector (pKS⁻), transformed into E. coli, isolated pSOY HMGR and used as a probe for Northern analysis. We demonstrate that expression of HMGR mRNA is correlated with strain-specific resistance (R). SMV coat protein (CP) degraded in vitro by proteolysis during purification. The CP of SMV purified from infected leaves had an major size of 34 kD in SDS-PAGE with minor peptides of 32 and 31 kD. The minor peptides increased during the storage at 4°C or with trypsin treatment, and reacted with antiserum to intact virions. This heterogeneity of protein was not removed by alkaline phosphatase treatment for varying time intervals, and was not related with phosphorylation and dephosphorylation, or with virus maturation. These studies provided additional evidence of N- or C-terminal exposure on the particle’s surface. / Ph. D.

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US market share of the Japanese soybean market declined from 91 percent in 1970 to a record low of 75 percent in 1989. In the Japanese market US soybeans compete against Brazilian soybeans. Brazilian soybean exports have increased as soybean production has expanded. Though US soybeans remained price competitive throughout the 1970-1989 study period, both volume and market share of US soybeans have decreased since 1985. The loss of market share indicates loss of competitive position. The demand for soybeans in the import dependent Japanese market is derived from the demand for the oilseed processed products of vegetable oil and protein meal. Through the Japanese tariff structure which taxes vegetable oil imports from countries outside the Pacific Rim and a private sector Japan/China barter agreement under which soy meal is imported from China, the relative demand for Japanese processed oilseed products has been influenced. Historically, US soybeans had lower levels of oil, and protein compared to Brazilian soybeans. A programming model of Japan feed-use oilseeds and oilseed processed products, vegetable oil and protein meal is developed to analyze non-price and price factors of competition for US soybean imports. / Master of Science

Sustainability of the soybean industry relies on the growth of new industries and the continued improvement of seeds for utilization. Grower adoption and growth of the edamame industry has been slow in part due to insufficient information on its potential profitability and marketability. As such, the first and second objectives of this thesis aimed at 1) determining production costs of hand-harvested fresh edamame enterprise and 2) exploring consumer willingness-to-pay (WTP) for fresh, local, organic, and "on-the-stalk" marketed edamame. Sucrose, raffinose, and stachyose sugars hold tremendous implications for utilization of soybean seeds in livestock, soyfood, and probiotics industries. Current sugar phenotyping methods using high-performance liquid chromatography (HPLC) are costly and inefficient. Therefore, the third objective of this study was to develop calibrations to predict sugar content using near-infrared reflectance spectroscopy (NIRS). Results showed that labor accounted for 72% of production costs for edamame pods, which largely limits its profit potential. Mean WTP for fresh and local edamame exceeded their frozen and non-local counterparts by 94 and 88 cents, respectively. In addition, mean WTP for organic edamame exceeded non-GMO edamame by 33 cents. Pro-environmental attitudes appeared to be a consistent driver of WTP these three attributes. Meanwhile, a 40-cent discount for "on-the-stalk" edamame compared to pods indicates convenience may also be a factor in edamame marketability. Calibration development for sucrose and stachyose was successful, with R2cal, R2cv, RMSEC, and RMSECV of 0.901, 0.869, 0.516, and 0.596, and 0.911, 0.891, 0.361, and 0.405, respectively. Alternative methods should be investigated for quantification of raffinose. / Master of Science / Sustainability of the soybean industry relies on the growth of new industries and the continued improvement of seeds for utilization. Grower adoption and growth of the edamame industry has been slow in part due to insufficient information on its potential profitability and marketability. As such, the first and second objectives of this thesis aimed at 1) determining production costs of hand-harvested fresh edamame and 2) exploring relative marketing potential of fresh, local, organic, and "on-the-stalk" edamame. Sucrose, raffinose, and stachyose sugars hold tremendous implications for utilization of soybean seeds in livestock, soyfood, and probiotics industries. Current methods of quantifying sugar are costly and time inefficient. Therefore, the third objective of this study was to develop prediction models to estimate sugar content using near-infrared reflectance spectroscopy (NIRS). Results showed that labor accounted for 72% of production costs for edamame pods, which largely limits its profit potential. Fresh and local edamame showed considerable marketing potential over frozen and non-local edamame. In addition, organic edamame showed marginal marketing benefit over non-GMO. Pro-environmental attitudes were an important driver of these results. Meanwhile, on-the-stalk edamame shows poor marketing potential, likely due to preference for convenience of food preparation in the U.S. NIRS prediction models for sucrose and stachyose showed strong predictive accuracy and low error, suggesting potential for implementation. The prediction model for raffinose, however, remained poor.