Dissertations and Theses @ UNI

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Open Access Thesis

Keywords

Barley--Effect of drought on; Plant proteomics;

Abstract

Drought is the major environmental factor that limits crop yield worldwide. Crops are particularly vulnerable to drought at the reproductive stage. In cereals, grain filling during drought depends on the contribution of current photosynthesis products from the leaf and spike and carbohydrates stored mainly in the stem and remobilized to the grain. Even though stem reserve is an important source for grain filling, changes in the proteome of barley stem under drought have not been studied. Also, the molecular events associated with differential stem reserve remobilization under drought are not well understood. In this study, barley plants were exposed to gradual drought over seven days at the grain filling stage to compare changes in the stem (penultimate) proteome of two barley varieties, Samson (drought susceptible) and Giza 132 (drought tolerant). We used isobaric tandem mass tag (TMTsixplex) and liquid chromatography-tandem mass spectrometry (LC-MS) to identify proteins in non-stressed control and drought-stressed stem in the two cultivars. A total of 2,467 proteins were identified, of which 38 proteins were significantly up-regulated and 6 proteins were down-regulation in Giza 132 in response to drought. Samson did not show any changes in its stem proteome in response to drought. The proteins that were up-regulated were grouped into proteolysis and the biosynthesis of flavonoids, polyamines, and aromatic amino acids. Down-regulated proteins include those involved in carbohydrate metabolism. Our results suggest that the stems of the drought tolerant barley (Giza 132) might contribute to improving drought resistance by reorganizing its proteome through proteolysis and increasing its cellular concentrations of flavonoids, polyamines, and aromatic amino acids while downregulating its carbohydrate metabolism.

Year of Submission

2022

Degree Name

Master of Science

Department

Department of Biology

First Advisor

Tilahun Abebe, Chair, Thesis Committee

Date Original

5-2022

Object Description

1 PDF file (ix, 83 pages)

Language

en

File Format

application/pdf

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