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Research Project: IMPROVE GRAIN SORGHUM END-USE QUALITY & UTILIZATION BY IDENTIFYING THE PHYSICAL, CHEMICAL & ENVIRONMENTAL FACTORS RELATED TO FOOD & FEED...

Location: Grain Quality and Structure Research

Title: Grain sorghum proteomics: An integrated approach towards characterization of seed storage proteins in kafirin allelic variants

Author
item Cremer, J - University Of Queensland
item Bean, Scott
item Tilley, Michael - Mike
item Ioerger, Brian
item Ohm, Jae-bom
item Kaufman, Rhett
item Wilson, Jeff
item Innes, David - Queensland Government
item Gilding, E - University Of Queensland
item Godwin, Ian - University Of Queensland

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2014
Publication Date: 9/1/2014
Publication URL: http://handle.nal.usda.gov/10113/59734
Citation: Cremer, J.E., Bean, S., Tilley, M., Ioerger, B.P., Ohm, J., Kaufman, R.C., Wilson, J.D., Innes, D., Gilding, E.K., Godwin, I.D. 2014. Grain sorghum proteomics: An integrated approach towards characterization of seed storage proteins in kafirin allelic variants. Journal of Agricultural and Food Chemistry. 62:9819-9831.

Interpretive Summary: Seed protein composition determines quality traits, such as value for food, feedstock and biomaterials uses. Because of this, an integrated proteomic approach was employed to characterize 28 sorghum lines with allelic variation at the kafirin loci in order to determine the effects of kafirin genetic diversity on the expression of seed proteins. This proteomic analysis compiles sequence and biochemical information describing a range of proteins affecting sorghum endosperm structure and composition. The derived dataset will further augment annotation of the sorghum proteome and facilitate identification of potential targets for improved grain quality. Furthermore our data provides a basis for comparative studies with other major grain crops. Possible avenues for utilizing protein sequence data include the development of high-lysine varieties with increased A/G content for enhanced nutritional quality, and the modification of enzyme-regulated protein aggregation in the endosperm for increased starch availability.

Technical Abstract: Seed protein composition determines quality traits, such as value for food, feedstock and biomaterials uses. Sorghum seed proteins are predominantly prolamins known as kafirins. Located primarily on the periphery of storage protein bodies, cysteine-rich ß- and gama-kafirins are thought to prevent enzymatic access to internally positioned alpha-kafirins and to starch. An integrated proteomic approach was employed to characterize 28 sorghum lines with allelic variation at the kafirin loci in order to determine the effects of kafirin genetic diversity on the expression of seed proteins. RP-HPLC and Lab on Chip analysis showed a reduction in alcohol-soluble protein in ß-kafirin null lines. Gel-based separation of seed proteins and subsequent LC-MS/MS profiling identified a range of redox active proteins affecting storage protein biochemistry. Thioredoxin, involved in processing of seed proteins during germination has reported impacts on grain digestibility and was differentially expressed across the genotypes. Thus redox states of endosperm proteins, of which kafirins are a subset, could affect quality traits in addition to expression of proteins.