Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 27, 2007) Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 85-91). Also available on the World Wide Web.

Master of Science / Department of Agronomy / William T. Schapaugh Jr / Yield in soybean (Glycine max (L.) Merr) needs to dramatically increase across the world to feed the growing population. Remote sensing and high-throughput phenotyping may provide a tool to better phenotype soybean genotypes. This research was conducted to: 1) examine the relationships between NDVI and CT with seed yield, maturity, lodging, and height, 2) determine if the time of day and growth stage have an effect on the spectral readings, 3) examine the relationships between spectral reflectance and traits associated with drought tolerance, and 4) evaluate how weather variables impact the ability of vegetative indices and canopy temperature to detect differences among genotypes. Ninety genotypes from the mapping population derived from the cross between KS4895 x Jackson were evaluated in Manhattan, KS, in 2013 and in McCune, Pittsburg, and Salina, KS in 2014. Genotypes were planted in a randomized complete bloc design in four-row, 3.4m long plots spaced 76 cm apart. Plant height, lodging, maturity and seed yield was collected on the center two rows of each plot. Spectral readings used to calculate a normalized differential vegetative index (NDVI) and canopy temperature (CT) were taken during reproductive growth. Nitrogen fixation trait and drought tolerance data was collected by the University of Arkansas. This population exhibited a substantial genetic variation for all traits evaluated. Correlations of NDVI and CT entry means with the agronomic traits were small and inconsistent. Time of day and growth stage were not important in differentiating genotypes. Differences in NDVI and CT did account for some genetic variation in drought tolerance traits, however, the strength of the associations were small. None of the weather variables were consistently associated with an increase or decrease in entry or error variance across the four environments. Stronger associations need to be established to use NDVI or CT to characterize differences in genotypes in a plant breeding program

Activity and transcription profiles of two classes of cysteine proteases, papain- and legumain-like cysteine proteases, as well as their potential inhibitors, cysteine protease inhibitors (cystatins), were investigated in soybean nodules during nodule development and after drought inducing premature senescence. During nodule development total protease activity increased with major activity bands detected protease zymography in older nodules. Expressed cysteine proteases during nodule development were detected by tagging proteases with the cysteine protease inhibitor DCG-04 with major DCG-04 tagged bands found in both young and old nodules. Increase in protease activity was associated with a significant decrease in nitrogenase activity of nodules measured as acetylene reduction. Semi-quantitative RT-PCR for cysteine protease and cystatin transcription profiling showed a decrease in transcription during development and also after drought treatment of several papain-like cysteine proteases (Glyma04g04400, Glyma17g05670, Glyma10g35100, and Glyma04g03090). In contrast, transcription of three legumain-like cysteine proteases (Glyma17g14680, Glyma05g04230 and Glyma14g10620) increased during nodule development and also after drought treatment. Transcription of two cystatins (Glyma13g27980 and Glyma05g28250) increased during nodule development with Glyma13g27980 strongly up-regulated after drought treatment and Glyma05g28250 constitutively strongly expressed in both well-watered and drought treated nodules. Overall, the study has contributed in establishing an expression profile of cysteine proteases and cystatins in soybean nodules. This knowledge provides a basis which can be used to determine the importance of the individual components of the cysteine protease – cystatin system, during soybean nodule development and during stress-induced premature nodule senescence. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Plant Science / unrestricted

One common method of improving the nutritional quality of certain food proteins is through fortification with necessary amounts of limiting essential amino acids. This simple and convenient method, however, is not the best. Several disadvantages are associated with the addition of free amino acids to food proteins, such as changes in flavor and color, losses of added amino acids during food processing or cooking, differences in stability and metabolism between free amino acids and amino acids in proteins. Covalent attachment of the limiting amino acids, however, should eliminate these problems, and moreover, could improve the nutritional and functional properties of food proteins. In this study, therefore, an attempt to improve the nutritional value of the soy protein was made by using the carbodiimide condensation reaction to covalently bind methionine and tryptophan to soy protein. In order to confine as much as possible the binding, of amino acid to the protein a-carboxyl groups the soy protein isolate (SPI) was partially hydrolyzed with pepsin to increase the number of a-carboxyls in soy protein. Various conditions of the carbodiimide reaction were analysed by a fractional factorial design in an attempt to determine the factors affecting the amino acid binding to soy protein hydrolysate (SPH). Of the factors investigated, pH, SPH concentration, carbodiimide concentration, activation time and reaction time were found to significantly affect the methionine binding efficiency, whereas pH, SPH concentration, carbodiimide concentration, amino acid concentration and reaction temperature were found to significantly influence the tryptophan binding efficiency to SPH. To determine the best level for each of the selected factors an optimization of the carbodiimide reaction conditions was conducted by carrying out another factorial experiment. Thus, under the best condition found, the methionine and tryptophan contents of methionine - and tryptophan-bound SPH samples were increased 7.7-fold and 18.0-fold, respectively. An in vitro pepsin-pancreatin digestion test demonstrated that the bound amino acids were readily released. In order to improve the low yield of the final product, another analysis of the carbodiimide reaction conditions was carried out. Since the yield could not be markedly improved by this factorial design in which peptic SPH was used, SPI without preliminary hydrolysis was used as the starting material. A product with 95-99% yield was obtained and its methionine or tryptophan content was increased 6.3-fold or 11.3-fold, respectively. High digestibility was still maintained for these products. Gel filtration chromatography demonstrated that the carbodiimide reaction caused an increase in the molecular weights of soy protein fractions. Furthermore, gel filtration chromatography revealed that, there was no selective amino acid binding among the different soy protein fractions during the carbodiimide reaction. / Land and Food Systems, Faculty of / Graduate

Soybean is one of the most important grain legumes grown in US and worldwide, and is a major component of human and animal protein diets. Despite improvements in management practices, and the introduction of improved soybean cultivars, soil borne pathogens continue to cause tremendous yield loss in soybean production each year. Among soil borne pathogens; Soybean Cyst Nematode (SCN) or Heterodera glycines together with Sudden Death Syndrome (SDS) induced by Fusarium virguliforme are responsible for the most damages in soybean fields. The most effective way to control these two pathogens is to develop resistant cultivars. Resistance to any population (HgType) of H. glycines, requires a functional allele at rhg1/Rfs2 locus. The rhg1/Rfs2 gene encodes a receptor-like kinase (RLK) protein. By analysing near isogenic lines (NIL) segregating for rhg1/Rfs2, rhg1-like loci were found at other locations most conservedly on LG B1. While the nature of rhg1 allele was thought to be recessive, heterozygous NIL segregating at the rhg1 locus showed that the resistant allele was dominant. Rhg1 was also inferred to be multigeneic due to absence of recombination between the RLK and other 2 genes. Functional and structural analyses were conducted on the leucine rich repeat (LRR) from RLK protein encoded by GmRLK18-1 within the Rhg1/Rfs2 locus. The LRR of GmRLK18-1 showed a high binding affinity to CLE-like peptides found in both nematode secretions and plant developmental control. Crosslinking assays and native gel analysis of GmRLK18-1-LRR validated its model as a crystal homo-dimer. Larger proteins were also shown to bind the LRR domain, in far-Western analyses both methionine synthase and cyclophilin bound strongly to the LRR domain. Homology and ab-initio modeling of the LRR domain of the GmRLK18-1 was predicted as both a monomer and a homodimer containing intrinsically unstructured regions. Amino acid substitutions found among GmRLK18-1 allotypes A87V, Q115K and H274N were predicted to play crucial roles in protein function and stability. The receptor like kinase (RLK) GmRLK18-1 within the Rhg1/Rfs2 locus underlies a pleiotropic resistance to both SCN and SDS. The resistance allele was shown to be dominant in both heterozygous NILs at Rhg1/Rfs2 and transgenics (hetero- or hemi-zygous). The RLK was found to provide a partial resistance to SCN and importantly a nearly complete resistance to both root and leaf symptoms of SDS. In the presence of Rhg4, the RLK-transgenic plants developed nearly full resistance to SCN. Therefore the RLK was proven to underlie a major portion of the Rhg1/Rfs2 locus.

Field experiments were conducted to determine the impact of threecornered alfalfa hopper, Spissistilus festinus, (Say), in reproductive growth stage soybeans. High densities of threecornered alfalfa hoppers were examined in field cages to understand feeding on soybean. No significant yield losses were observed from threecornered alfalfa hopper feeding during reproductive growth stages. Sweep net efficiency studies were conducted in order to convert the densities used in field cages to a sweep net threshold. Field experiments were also conducted to determine the impact of threecornered alfalfa hopper injury to seedling cotton. Threecornered alfalfa hopper injury to seedling cotton plants impacts individual plant yield, but further research is needed to understand the ability for undamaged cotton plants to compensate for neighboring damaged plants.

Experiments were conducted to evaluate the most profitable and effective management practices for non-irrigated soybean production. Common production practices were compared side by side to evaluate yield response and economic returns. Combinations of row spacings and planting dates were evaluated to determine interactions between the two factors and also the effects on yield. Lastly, the effectiveness of various iron sources was examined in iron deficiency chlorosis (IDC) susceptible soybeans when applied foliar, inurrow at planting, and a split application. These data suggest that in non-irrigated soybeans, “low input management” practices do not maximize yields, but can be more profitable, depending on soybean market price and input costs, when compared to “full management”. Results also reveal that no interaction between row spacing and planting date occurred with respect to soybean yield. However, planting date did influence soybean yield with the earlier planting dates, mid-April, and mid-May providing the greatest yield. When examining row spacing, soybean grown on rows spaced 38.10 cm apart resulted in greater yield when compared to those grown on 96.52 cm rows. The iron product that consistently provided the greatest visual reduction of IDC symptoms was Sequestar 6% EDDHA chelate applied at 0.20 and 0.27 kg ai ha-1. This treatment was only effective when applied inurrow at planting. However, it was found that soybean yield was not influenced by any iron product or application timing, indicating that visual symptoms of IDC may be managed, but that the visual reduction in symptoms does not translate into yield.

Stink bugs (Hemiptera: Pentatomidae) are key pests of soybean, Glycine max (L.), in Mississippi. Historically, yield loss derived from direct feeding by stink bugs has been considered the greatest threat to producers. However, quality reductions resulting from seed infections caused by microorganisms including Phomopsis longicolla are also a concern. Experiments were conducted in 2010 and 2011 to determine if stink bugs are associated with the incidence of P. longicolla in Mississippi soybean production. Data from experiments suggest that stink bugs are capable of transporting P. longicolla between two points. Data further suggest stink bugs and P. longicolla have the potential to cause a yield loss of 20% when combined in soybean. Surveys of commercial fields in Mississippi determined that stink bug damaged seed was more likely to be infested with P. longicolla and other fungi compared to undamaged seed.

No description available.