Date of Award

8-2009

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Plant and Environmental Science

Advisor

SHIPE, EMERSON R

Committee Member

SEHORN , MICHAEL G.

Committee Member

KNAP , HALINA T.

Committee Member

LUO , HONG

Abstract

Global population is expected to increase 30% by 2040, which will result in an increased need for crop production to feed the growing population. Combined with projected increased drought conditions worldwide, plant genetic research is necessary to gain a deeper knowledge of the molecular factors involved in plant drought response in order to engineer crop species with improved drought tolerance. Aquilegia has been recently developed as a model species for gene exploration based on its ability to thrive in a wide variety of environments including arid locations. An attractive asset of Aquilegia is its evolutionary position, equidistant between rice and Arabidopsis. Multifaceted molecular biology techniques were employed in these studies to identify biological components associated with Aquilegia's response to drought. Techniques utilized were; suppression subtractive hybridization, using drought-stressed and un-stressed tissue-derived mRNAs to selectively amplify differentially expressed genes, metabalomic profiling as a means to examine the identity and possible function of accumulated metabolites, and exploration of proteomes obtained under different levels of drought stress. Subtractive hybridization yielded numerous sequences such as DREB known to be involved with drought and other genes with no known association to drought response. The metabalomics approach yielded vitexin and vitexin 2'-O-β-D-glucoside, identified via LCMS and HPLC. Vitexin concentration within Aquilegia leaf tissue increased 357% over the time course of the drought experiment. Previously, vitexin had not been associated with drought response. Proteome analysis identified various proteins known to play some defensive role in drought stress. This parallel initiative yielded numerous possible gene candidates for genetic engineering of crop species. Results from this project confirm Aquilegia's role as an excellent genetic resource for studying responses to a wide range of abiotic stresses, specifically drought.

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