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dc.contributor.advisorBraun, David M.eng
dc.contributor.authorDhungana, Singha Rajeng
dc.date.embargountil5/31/2023
dc.date.issued2022eng
dc.date.submitted2022 Springeng
dc.description.abstractCarbohydrate partitioning, the process by which carbohydrates synthesized in the photosynthetic source tissues (mature leaves) are mobilized to non-photosynthetic (sink) tissues, such as roots, seeds, and developing organs is crucial for plant growth, development, and yield. Various physiological, biochemical, and anatomical studies have addressed this process, but the genetic control of carbohydrate partitioning is still not well understood. The main purpose of this dissertation is to elucidate aspects of the genetic control of carbohydrate partitioning in maize and sugarcane. Chapter 1 summarizes our current knowledge of phloem loading in grasses, the principal families of sugar transporters involved in sucrose transport, and novel mechanisms by which the activities of these sugar transporters are modulated. It also elaborates some of the recent discoveries in some eudicot species. Chapter 2 describes the genome of the wild ancestor of sugarcane (Saccharum spontaneum) and presents some ideas about the genes that may regulate sugar storage in the modern sugarcane varieties. For this study, I annotated Sucrose Transporters (SUTs) and Tonoplast Sugar Transporters (TSTs) in the S. spontaneum genome. Similarly, Chapter 3 describes the sugar transporter families; SUTs and TSTs in low (Saccharum spontaneum) and high sugar accumulating (Saccharum officinarum) sugarcane species and takes a comparative genomics approach to understand the ability of modern sugarcane cultivars to store huge amounts of sugars in their stem. Chapter 4 describes the characterization and cloning of maize carbohydrate partitioning defective13 (cpd13) and carbohydrate partitioning defective35 (cpd35) mutants, whereas Chapter 5 describes the characterization and progress towards cloning of carbohydrate partitioning defective60 (cpd60) and carbohydrate partitioning defective87 (cpd87) mutants. All of these mutants are recessive and contribute to carbohydrate hyperaccumulation in the mature leaves of the mutant due to reduced sucrose export. The cpd13 and cpd35 mutations affect a Dna-J-thioredoxin-like protein, which is hypothesized to be involved in processing of proteins and have chaperone-like activities. The cpd60 and cpd87 mutations result in ectopic lignin in the phloem of mature leaves, but the mechanism and the gene involved remain to be identified. Chapter 6 summarizes the discoveries made in the previous chapters and presents future research directions. Appendix A is a research article that I collaborated on and contributed to the measurement of non-structural carbohydrates in very oil yellow1 (vey1) leaves introgressed to B73 and Mo17 inbred lines. Collectively, the research presented here has enhanced our understanding of the genetic control of carbohydrate partitioning in maize and sugarcane. These studies establish the foundations for future experiments to determine the genetic architecture controlling carbohydrate partitioning in plants.eng
dc.description.bibrefIncludes bibliographical references.eng
dc.format.extentxvi, 280 pages : illustrations (color)eng
dc.identifier.urihttps://doi.org/10.32469/10355/91661eng
dc.identifier.urihttps://hdl.handle.net/10355/91661
dc.languageEnglisheng
dc.publisherUniversity of Missouri--Columbiaeng
dc.relation.ispartofcommunityUniversity of Missouri--Columbia. Graduate School. Theses and Dissertationseng
dc.titleDissecting the genetic basis of carbohydrate partitioning in maize and sugarcaneeng
dc.typeThesiseng
thesis.degree.disciplineBiological sciences (MU)eng
thesis.degree.grantorUniversity of Missouri--Columbiaeng
thesis.degree.levelDoctoraleng
thesis.degree.namePh. D.eng


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