Poster: Protein modification
Abs #
812: Engineering of storage protein composition and bread making quality in rye (Secale cereale L.)
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Presenter: |
Altpeter, Fredy , faltpeter@mail.ifas.ufl.edu | Authors | Altpeter, Fredy (A) Popelka, Juan C (B) Wieser, Herbert (C) Kiefer, Rolf (C) | | Affiliations: |
(A): University of Florida - IFAS
(B): CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia
(C): Deutsche Forschungsanstalt fuer Lebensmittelchemie (DFA), Lichtenbergstr. 4, 85748 Garching, Germany
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| Web Site: | http://agronomy.ifas.ufl.edu/Altpeter.HTML | |
We generated and characterized transgenic rye synthesizing substantial amounts of high-molecular-weight glutenin subunits (HMW-GS) from wheat. Rye flour has poor bread-making quality, despite the extensive sequence and structure similarities of wheat and rye HMW-GS. The HMW-GS 1Dx5 and 1Dy10 genes from wheat, associated with good bread making quality, were introduced into rye by biolistic gene transfer. The transgenic plants transmitted the transgenes stably to the sexual progeny, as shown by Southern blot and SDS-PAGE analysis. Flour proteins were extracted by means of a modified Osborne fractionation from wildtype (L22) as well as transgenic rye expressing 1Dy10 (L26) or 1Dx5 and 1Dy10 (L8) and were quantified by RP-HPLC and GP-HPLC. The amount of transgenic HMW-GS in homozygous rye seeds represented 5.1 % (L26) or 16.3 % (L8) of the total extracted protein and 17 % (L26) or 29 % (L8) of the extracted glutelin fraction. The amount of polymerized glutelins was significantly increased in transgenic rye (L26) and more than tripled in transgenic rye (L8) compared to wildtype (L22). Gel permeation HPLC of the un-polymerized fractions revealed that the transgenic rye flours contained a significantly lower proportion of alcohol-soluble oligomeric proteins compared with the non-transgenic flour. The quantitative data indicate that the expression of wheat HMW-GS in rye leads to a high degree of polymerization of transgenic and native storage proteins, probably by formation of intermolecular disulfide bonds. Our results demonstrate that the addition of HMW-GS to rye allow to influence the degree of polymerization of native storage proteins. Impact on functional properties will be discussed.
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