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dc.contributor.advisorChairperson, Graduate Committee: Michael J. Girouxen
dc.contributor.authorJobson, Emma Marieen
dc.contributor.otherM.J. Giroux, J.M. Martin, R.E. Johnston and A.J. Oiestad were co-authors of the article, 'The impact of the wheat RHT-B1B semi-dwarfing allele on photosynthesis and seed development under field conditions' in the journal 'Frontiers in plant science' which is contained within this dissertation.en
dc.contributor.otherM.J. Giroux, J.M. Martin and T.M. Scheider were co-authors of the article, 'The impact of the RHT-B1B, RHT-D1B, and RHT-8 wheat semi-dwarfing genes on flour milling, baking, and micronutrients' in the journal 'Cereal chemistry' which is contained within this dissertation.en
dc.contributor.otherM.J. Giroux, J.M. Martin and J.B. Ohm were co-authors of the article, 'RHT-1 semi-dwarfing alleles alter dough rheology by modifying gluten composition' submitted to the journal 'Cereal chemistry' which is contained within this dissertation.en
dc.contributor.otherM.J. Giroux, J.M. Martin and A.C. Hogg were co-authors of the article, 'Identification and molecular characterization of novel RHT-1 alleles in hard red spring wheat' submitted to the journal 'Crop science ' which is contained within this dissertation.en
dc.description.abstractSince their introduction in the 1960s, the semi-dwarfing Reduced Height (Rht-1) genes in wheat have been incorporated into the majority of modern wheat varieties. Their popularity has been driven by their positive impact on yield. The two most common semi-dwarfing alleles, Rht-B1b and Rht-D1b, reduce height ~20% and increase yield ~6% compared to tall varieties. Their shorter stature makes them less susceptible to lodging under increased water and nitrogen inputs compared to tall wheat varieties. Despite their prevalence, the exact mechanism by which Rht-B1b/Rht-D1b increase yields is still unknown. Furthermore, very little research has been done to characterize their impact on bread making and end use quality. Finally, beyond Rht-B1b and Rht-D1b, there is very little allelic diversity available to wheat breeders. The objectives of this research were to investigate the impact of Rht-B1b on photosynthesis, characterize the impact of Rht-B1b/Rht-D1b on bread making and dough rheology, and to identify and test novel Rht-1 alleles created using EMS mutagenesis. In regards to photosynthesis: we found Rht-B1b reduces flag leaf photosynthetic rate (18%) and chlorophyll A content (23%) compared to the tall wildtype at anthesis. In regards to end use quality: we found Rht-B1b/Rht-D1b decrease total grain protein content (2%) but increase gluten index (21%), bake mixing time, and bake mixing tolerance compared to the tall lines. Increased gluten index and mixing time in the semi-dwarfing lines was shown to be associated with increased high molecular weight glutenins. In regards to developing novel alleles: we identified three nonsense Rht-1 alleles and characterized their impact on coleoptile length, gibberellin responsiveness, and DELLA/GID1 interaction. Further research will be needed to investigate their impact on agronomic traits and found that each abolished GID1 interaction in the absence but not the presence of Gibberellic acid. Overall this dissertation provides new insight on the impact of the semi-dwarfing alleles on wheat growth and development, wheat milling and baking properties and increases the available allelic diversity through the introduction of three new Rht-1 nonsense alleles.en
dc.publisherMontana State University - Bozeman, College of Agricultureen
dc.subject.lcshPlant breedingen
dc.subject.lcshVariation (Biology)en
dc.subject.lcshCrop yieldsen
dc.subject.lcshQuality of productsen
dc.titleCharacterization and identification of novel reduced height (RHT-1) alleles in wheaten
dc.rights.holderCopyright 2019 by Emma Marie Jobsonen, Graduate Committee: Jack Martin; Philip L. Bruckner; Andreas M. Fischer; Robert Sharrocken Sciences & Plant Pathology.en

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