Extraction and Direct Quantification of Salicylic Acid in Arabidopsis Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

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Title: Extraction and Direct Quantification of Salicylic Acid in Arabidopsis Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry
Author: Ganawi, Amel Ahmed A.
Advisors: Lin He, Committee Chair
David C. Muddiman, Committee Member
Wendy F. Boss, Committee Member
Abstract: Systemic acquire resistant (SAR) is enhanced resistance created by the plant after infection, in which the plant becomes resistant to a second pathogen infection. This resistant can last for weeks preventing the plant from being infected. In addition the plant becomes resistant not only to the pathogen that causes the infection but also to a wide range of pathogens.Knowing how to activate this resistant in the plant is critical to increase crop production. Salicylic Acid has been suggested as one of the main signaling compounds to activate SAR after plant infection. I describe here the development of a matrix assisted laser desorption ionization mass spectrometry (MALDI-MS)-based approach to monitor SA in Arabidopsis thaliana. Sinapic acid was identified as the preferred choice in SA detection because minimal interference was observed between the matrix and analyte peaks. The use of Isotopic labeled Salicylic Acid (SA-d6) as a suitable internal standard for SA quantification was also demonstrated.SA spiked in plant extract at known concentrations was used as the model system to evaluate quantification and reproducibility of this newly developed MALDI-MS method. A comparison in detection feasibility between MALDI-MS and DIOS-MS was also conducted and reported in this thesis. In addition, a Liquid-phase extraction method is optimized to yield maximal extraction efficiency. I have quantified extraction efficiency and method reproducibility to extract SA in Arabidopsis leaves, and demonstrated its applicability for quantitation of endogenous SA in different plant samples.
Date: 2007-12-04
Degree: MS
Discipline: Chemistry
URI: http://www.lib.ncsu.edu/resolver/1840.16/328


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