Date of Award

Winter 2011

Project Type

Dissertation

Program or Major

Plant Biology

Degree Name

Doctor of Philosophy

First Advisor

Subhash Minocha

Abstract

The metabolism of polyamines (Putrescine, Spermidine and Spermine) in wild type and transgenic Arabidopsis thaliana (Col 0 ecotype) plants was studied using the techniques of transgenic manipulation and gene expression. Two specific objectives were: (1) To study the effects of inducible and constitutive transgenic manipulation of polyamines via a mouse ornithine decarboxylase (mODC) gene on plant metabolism. (2) To analyze the spatial and temporal expression patterns of Arabidopsis thaliana S-adenosylmethionine decarboxylase genes (AtSAMDC3, AtSAMDC4 and AtSAMDC5) during its life cycle.

The major findings are: (i) Orn becomes a limiting substrate for Put biosynthesis in transgenic Arabidopsis expressing mODC gene, (ii) Put over-production cause delayed flowering, increased FW and DW, higher silique number and higher chlorophyll content, (iii) the cellular contents of several amino acids change under constitutive as well as short term induction of mODC, (iv) there is a greater utilization and assimilation of carbon and nitrogen into polyamines and amino acids by the mODC -transgenic plants, (v) different members of the AtSAMDC gene family are expressed differently in different tissues/organs during development, (vi) expression of AtSAMDC4 is much higher than AtSAMDC3 and AtSAMDC5, (vii) the promoter regions of all AtSAMDC genes contain common cis-regulatory elements that are associated with stress responses, developmental regulation, and hormone responses.

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