Date of Award


Degree Type


Degree Name

Doctor of Philosophy




Dr. Daniel Brown

Second Advisor

Dr. Mark Gijzen

Third Advisor

Dr. Mark Bernards


The seed coat arises from maternal integuments and its main role is the protection of the developing embryo. At maturity the soybean seed coat is composed mainly of dead cells that impart protection, enable germination and enhance dispersal. Soybean seed coat is an agricultural-by product that is currently under utilized, although some reports have found diverse applications that are currently explored. Using gel-based pre fractionation of proteins followed by electro spray ionization tandem mass spectrometry, a comprehensive proteomic database of physiologically mature soybean seed coats was created. Around 150,000 spectral was acquired and used to challenge current protein databases. The gene ontology assignment of over 1,000 seed coat proteins allowed a correlation with important seed metabolic pathways such as cell wall biosynthesis, proteolytic pathway, synthesis of amino acids, carbohydrates and nucleotides thorough the Ci metabolic pathway, fatty acids and isoflavonoids. The most abundant protein in the soybean seed coat is methionine synthase. Besides the synthesis of methionine, it could be associated with the production of ethylene in the seed coat, promoting fruit ripening. There is an apparent increase in the relative amount of metabolic proteins at the onset of seed maturation. This finding suggests that the seed coat remains metabolically active for a longer time than the embryo. Proteases are an important protein group in the seed coat proteome and are most likely involved in tissue remodelling. They could also be further studied as potential candidates for catalysis of industrial reactions. A comprehensive protein database is reported along with protein ontology assignments. The correlation of proteomic and transcriptomic data for specific proteins allowed the identification of control mechanisms of protein expression in the seed coat. This will be very valuable in future molecular-based approaches to in modify the seed coat proteome in order to control aspects of seed development, and also as a target organ for the heterologous expression of proteins.



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