Date of Award

Winter 2015

Project Type

Thesis

Program or Major

Plant Biology

Degree Name

Master of Science

First Advisor

Subhash C Minocha

Second Advisor

Matthew D MacManes

Third Advisor

Rakesh Minocha

Abstract

Polyamines (PA), primarily putrescine (Put), spermidine (Spd), and spermine (Spm), are small, nitrogen-rich molecules with important roles in plant development, stress response, and regulation of cellular nitrogen (N) content. Work on increased PA biosynthesis has been performed in the Minocha lab using the mouse ornithine (Orn) decarboxylase (mODC) transgene engineered with a constitutive or an estradiol-inducible promoter. Though most studies of transgenic plants are done using constitutive regulation long-term PA over-production in transgenic high Put cells leads to alterations in metabolism, oxidative state, and C:N ratios. Thus, constitutive regulation may not be a reliable representation of events experienced by plants in nature and inducible regulation may be more appropriate. The goal of this experiment was to use RNA-seq analysis to characterize the expression profiles of inducible mODC, constitutive mODC, and wild type Arabidopsis seedlings, specifically contrasting inducible versus constitutive mODC regulation. Differential expression analysis demonstrated that high PA Arabidopsis samples, whether constitutive or inducible, had very similar expression profiles to wild type plants. Lack of differential expression of PA pathway related genes also supports previous studies that showed PA pathway genes to be regulated post-transcriptionally. Improving our understanding of the cascade effects of engineered increased PA production using RNA-Seq data informs future research and helps determine appropriate promoter::gene usage for future studies on transgenic approaches to metabolic engineering.

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