Poster: Seed Biology
Abs #
551: Lysine metabolism in the opaque and floury mutants of maize
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Presenter: |
Lea, Peter J, p.lea@lancaster.ac.uk | Authors | Lea, Peter J (E) Azevedo, Ricardo (A) Toro, Alejandro A (A) Varisi, Vanderlei A (A) Berdejo, Bertha DA (A) Medici, Leonardo O (A) Le Guilloux, Martine (B) Damerval, Catherine (B) Bellato, Claudia M (C) Meinhardt, Lyndel W (A) Delhaye, Sonia (D) Landry, Jacques (D) Gaziola, Salete (A) | | Affiliations: |
(A): Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba CEP 13400-970, SP, Brazil;
(B): Station de Génétique Végétale, La Ferme du Moulon, 91190 Gif-sur-Yvette, France
(C): Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba CEP 13400-970, SP, Brazil
(D): INRA, Laboratoire de Chimie Biologique, INA-PG, F78850 Thiverval-Grignon, France
(E): Department of Biological Sciences, University of Lancaster, Lancaster LA1 4YQ, United Kingdom
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Although considerable information is available concerning lysine metabolism in the opaque-2 maize mutant, little is known about other similar mutants classified as high-lysine and exhibiting an opaque phenotype, such as opaque (o) mutants 1, 5, 6, 7, 9, 10, 11, 13 and 14, and the floury (fl) mutants 1, 2 and 3. A comprehensive investigation into these mutants was initiated with the aim to obtain new insights into the regulation of the lysine metabolism in maize. We have carried out a detailed biochemical characterization of these mutants, following a quantitative and qualitative study of the N constituents of endosperm. The information obtained has included total protein, nonprotein N, soluble amino acids, albumins/globulins, zeins and glutelins together with the enzymes involved in lysine biosynthesis and degradation during endosperm development.
The o2 mutant exhibited the highest relative concentration of free lysine followed by the fl2 mutant, whereas the o11, o5 and fl3 exhibited lower relative concentrations of free lysine when compared to their wild-type counterparts. Based on 2D-PAGE analysis of zeins, 52 zein polypeptides were detected among the 14 genotypes tested. In general, the mutations decreased the number of zein isoforms detected on the 2D gels, indicating a decreased zein amount and diversity.
The activity and end product inhibition of AK varied considerably among the genotypes, with fl3 being the lowest and the wild-type B37+, the highest. The activity of HSDH was lowest in o13 and highest in the o2 mutant. The enzymes LOR and SDH, both involved in lysine degradation exhibited large variations, particularly for LOR activity. The o2 and fl2 mutants exhibited 6 and 7 fold reductions in LOR activity, when compared to the wild-type maize lines
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