Date of Award

Spring 2022

Project Type

Thesis

Program or Major

Genetics

Degree Name

Master of Science

First Advisor

Subhash Minocha

Second Advisor

Rakesh Minocha

Third Advisor

Anissa Poleatewich

Abstract

Polyamines are a class of low molecular weight, nitrogenous bases that participate in many important functions in plants, from germination to senescence and many steps in between. These molecules have been shown to play key roles in various abiotic and biotic stress responses which makes their biosynthetic pathway a focal point for engineering plants to better adapt to rapidly changing local environments and global climate change. Previous work with plants capable of producing high polyamine titers shows that they have superior stress responses as compared to their wild type counterparts. This study investigated what broader impacts a genetic manipulations to a basic metabolic pathway may have on the overall profile of gene expression of young plants of Arabidopsis thaliana. We investigated the effects of these transgenic changes, in model system A. thaliana, in plants with the conferred trait of polyamine overproduction, specifically putrescene, by way of transgenic manipulation using a mouse (Mus musculus) ornithine-decarboxylase (ODC) gene, which has been used extensively over the years for this purpose. Employing Next Generation Sequencing (NGS) technology, we compared the transcriptomic differences between wild type plants and those genetically engineered to live with high putrescine either constitutively or in response to short-term induction. Our results show that polyamine overproduction has wide-ranging impacts on not only the neighboring pathways of amino acids and their closely related sub-pathways but also plant growth regulator biosynthetic pathways (e.g., the abscisic acid metabolic pathway), specifically in relation to stimulating a stress response – even in the absence of a traditional stressor. This enhancement of polyamine biosynthesis and accumulation shows the promise of metabolic genetic engineering as a way to produce stress-tolerance in plants, and potentially increased nitrogen and carbon assimilation leading to higher biomass accumulation.

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