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Title: GLOBULINS ARE THE MAIN SEED STORAGE PROTEINS IN BRACHYPODIUM DISTACHYON

Author
item L Chingcuanco, Debbie
item Vensel, William

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2008
Publication Date: 6/5/2008
Citation: Chingcuanco, D.L., Vensel, W.H. 2008. Globulins are the main seed storage proteins in brachypodium distachyon. Theoretical and Applied Genetics. 117:555-563.

Interpretive Summary: The phylogenetic placement of Brachypodium makes it a more appropriate system than rice, the traditional monocot model organism, to explore agronomic traits of interest in temperate grasses, which includes important crops like wheat, barley and oat. To begin to investigate its utility as an experimental model plant to dissect grain development and grain filling we identified its major seed storage proteins. Storage proteins account for about half the seed proteins in cereals, thus, is a major source of protein in human diet. Understanding the mechanism of seed storage protein synthesis, trafficking and deposition could provide insights in developing effective approaches to improve cereal grain nutritional quality and functional properties in end-use products.

Technical Abstract: Brachypodium distachyon is being developed as a model system to study temperate cereals and forage grasses. We have begun to investigate its utility to understand seed development and grain filling by identifying the major seed storage proteins in a diploid accession Bd21. With the use of 1-dimensional SDS-PAGE and mass spectrometry we detected seven major storage protein bands, 6 of which were identified as globulins. A subset of the major seed proteins isolated from 3 hexaploid accessions, Bd4, Bd14 and Bd17 were also identified as globulins. Several Brachypodium cDNAs clones encoding globulin were completely sequenced. Two types of globulin gene were identified, Bd.glo1 and Bd.glo2, which are similar to maize 7S and oat12S globulins, respectively. The derived polypeptide sequences of the globulins contain a typical signal peptide sequence in their polypeptide N-termini and 2 cupin domains. Bd.glo1 is encoded by a single copy gene, whereas, Bd.glo2 belongs to a gene family.