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A Robust Agroinfiltration Method, Bryce N. Trull

Masters Theses

Stable transformation of soybean (Glycine max) is a markedly slow and laborious process. Thus, a tool that enables rapid evaluation of genetic elements in planta is critical to advance complex research and genetic engineering in soybean. To that end, a substantially robust agroinfiltration method was innovated in this work. Agroinfiltration is a technique that leverages Agrobacterium-mediated transient transformation to deliver genetic elements to the cells of whole plant tissues, usually leaves. Several factors were found to be relevant to successful soybean leaf agroinfiltration, including genotype, surfactant, developmental stage, and Agrobacterium culture medium. The research represents not only …

Role Of Kinases And An Epigenetically Regulated Gene In Soybean Cyst Nematode Resistance, Tracy Elizabeth Hawk

Doctoral Dissertations

Soybean cyst nematode (SCN) is the most devastating and economically important pathogen of soybean across the United States and globally. The current primary control for SCN is with the use of resistant cultivars, however, SCN populations are shifting to overcome most common sources of soybean resistance. This research was conducted to identify novel sources of genetic resistance to SCN. First, I functionally characterized two protein kinase hub genes whose function are predicted to be essential for mediating soybean susceptibility to SCN. I generated kinase-dead variants by mutating two amino acids required for the kinase enzymatic activity. Overexpression of the kinase-dead …

Characterization And Management Of Auxin-Resistant Palmer Amaranth In Tennessee, Delaney C. Foster

Doctoral Dissertations

Palmer amaranth has a long history of evolving resistance to herbicides to the point it has become a significant row crop production obstacle. Cotton and soybean growers were offered new technologies in 2016, expanding in-crop herbicide options to include dicamba or 2,4-D. Within three years of commercialization, dicamba use in these crops increased ten-fold and growers began to report Palmer amaranth escapes in west Tennessee auxin-tolerant production systems. A survey of Palmer amaranth escapes in dicamba and 2,4-D-tolerant cotton and soybean fields in Tennessee was conducted in the fall of 2021 with the objective of determining if poor control was …

Functional Analysis Of Soybean Proteinase Inhibitor Genes And Cyst Nematode-Inducible Synthetic Promoters For Insects And Nematode-Resistance In Plants, Mst Shamira Sultana

Doctoral Dissertations

Proteinase inhibitors (PIs) from legumes have the potential for use as protectants in response to pests and pathogens. Soybean (Glycine max) contains two trypsin inhibitors (TIs): Kunitz trypsin inhibitor (KTI) and Bowman-Birk inhibitor (BBI). In this study, the possible role of soybean TIs in plant defense against insects and nematodes was investigated. In addition to the three known TIs (KTI1, KTI2 and KTI3), novel inhibitors KTI5, KTI7, and BBI5 were identified in soybean. Their functional role was further examined by overexpression in soybean and Arabidopsis. In vitro enzyme inhibitory assays showed significant increase in trypsin and chymotrypsin inhibitory …

Relative Soybean Response To Aminocyclopyrachlor, 2,4-D, Dicamba, And Aminopyralid, Trey I. Clark

Masters Theses

This research compared the visual symptomology of four auxin herbicides applied at three rates to simulate tank contamination on non-auxin tolerant soybeans. The herbicides examined were aminocyclopyrachlor (ACP), 2,4-D, dicamba, and aminopyralid. The standard labeled rates (SLR) used to base the application rates were 0.12 kg ae ha^-1 for ACP and aminopyralid while dicamba and 2,4-D used 1.12 kg ae ha^-1. These four herbicides exhibit similar symptoms on soybeans which is problematic when diagnosing soybean response. One goal of this project was to obtain high-quality images of the four herbicide’s effect on soybeans, with the hope of …

Fungicide Sensitivity Screening Of Corynespora Cassiicola In Us Soybean And Cotton, Tyler Miles Smith

Doctoral Dissertations

Target spot, caused by the fungus Corynespora cassiicola, is a foliar disease of cotton and soybean. Target spot has become a disease of concern in soybean and cotton production systems. Data for fungicide sensitivity and understanding potential impact on yield is lacking for C. cassiicola. Fungicide resistance is also a concern in C. cassiicola with the increase in resistant pathogens in soybean. With the lack of knowledge about baseline fungicide sensitivity and the concern of fungicide resistance the objectives of this study were: (i) to evaluate fungicide products and mixes in small plot soybean and cotton trials, (ii) …

Identifying Drought Tolerance Traits In Tennessee Soybean Genotypes: Recovery From Severe Water Deficit Stress, Samuel W. Purdom

Masters Theses

Ninety-four percent of U.S. grown soybeans are produced under rainfed conditions with intermittent droughts occurring late in the season during reproductive growth stages. Due to the temporary nature of drought, the ability of a crop to survive and recover effectively from water deficit stress is important for ensuring yield stability. In 2019 and 2020, two greenhouse experiments and two field studies were conducted to screen eleven soybean genotypes for transpiration response and recovery from water deficit stress and high vapor pressure deficit (VPD). In the first greenhouse study, soybean plants were grown in pots sealed to prevent evaporation and plants …

Effect Of The Mutant Danbaekkong Or Stem Termination Alleles On Soybean Seed Protein Concentration, Amino Acid Composition, And Other Seed Quality And Agronomic Traits, Mia Justina Cunicelli

Masters Theses

Soybean [Glycine max (L.) Merr.] is the world’s leading source of vegetable oil and high quality protein meal. Increasing soybean protein concentration through selection while maintaining oil concentration and yield has been a constant goal for plant breeders, as there is a negative correlation between protein and oil and protein and yield. The objective of this study was to determine if marker assisted selection (MAS) for the Danbaekkong (Dan) protein allele influences agronomic and seed quality traits. A population of 24 F_8:10 [eighth filial generation advanced to the tenth filial generation] near isogenic lines (NILs) of soybean was …

Molecular Breeding Strategies For Improvement Of Complex Traits In Soybean, Christopher Joseph Smallwood

Doctoral Dissertations

Soybean [Glycine max (L.) Merrill] is the leading oilseed crop grown in the world. Yield, fatty acids, protein, and oil are commercially important soybean traits; thus evaluation of breeding strategies for improvement of these traits is merited. To accomplish this, a comparison of molecular and phenotypic breeding strategies from progeny row selections was performed. From this it was determined that molecular strategies consistently outperformed phenotypic selections (PS) in the progeny row stage for soybean yield, fatty acids, protein, and oil. For yield, Epistacy was the preferred selection method. For fatty acids, protein, and oil, the genomic selection (GS) strategies were …

Effects Of Leaflet Orientation And Root Morphology On Physiological Traits And Yield In Soybeans., Richard Dewayne Johnson

Doctoral Dissertations

Drought is the most important abiotic stress adversely affecting soybean (Glycine max (L.) Merr.) yield. Leaflet orientation has been shown to reduce leaflet temperatures and transpiration while root morphology has been related to slower wilting phenotypes. The objective of this study was to investigate effects of leaflet orientation and rooting morphology on whole plant transpiration, yield, water use efficiency, and other physiological traits in soybeans using grafting techniques, population lines, near-isogenic lines, and restrained leaf canopy experiments. Experiments were conducted in Knoxville, TN with additional yield trial plots at Springfield, Spring Hill, and Milan, TN. Data were collected on …

Comparison Of Roundup Ready And Conventional Soybean (Glycine Max L.) Weed Control Systems For Optimizing Yield And Economic Profitability, Brittany Lee Gaban

Masters Theses

Research was conducted in 2010, 2011 and 2012 at the East Tennessee Research and Education Center in Knoxville, TN, in order to compare differences in soybean yield among differing levels of weed control within Roundup Ready® [Glyphosate-resistant] (RR)and conventional soybean cultivars to gain a better understanding of the impact different intensities of weed control have on RR and conventional cropping systems. Results determined that after applying the weed control regimens, there was no significant difference (p

Glyphosate resistant weeds introduce new challenges and create a more costly weed control regimen, especially when using a RR based soybean cultivation operation. Therefore, …

Heritability And Genetic Gain Of Seed Protein, Oil, And Yield Among Ril Of Soybean, Benjamin T. Wiggins

Masters Theses

Soybean is a remarkable crop that is used in many aspects of our everyday lives. The seed protein is used primarily for livestock feed, though it is becoming more available as a meat substitute for human consumption. Soybean oil is used in many products such as plastics, foods, and industrial products. Seed yield is the major trait that is selected for in a breeding program. A population of 239 F₄ derived RIL from the cross of USG 5601T × U99-310255 was used to calculate heritability estimates by parent offspring regression and on an entry mean basis. This population was …