Plant Molecular Biology

, Volume 34, Issue 1, pp 139–149

Lysine-rich modified γ-zeins accumulate in protein bodies of transiently transformed maize endosperms

  • Margarita Torrent
  • Iñaki Alvarez
  • M. Isabel Geli
  • Ionara Dalcol
  • Dolors Ludevid
Article

Abstract

During maize seed development, endosperm cells synthesize large amounts of storage proteins, α-, β, and γ-zeins, which accumulate within endoplasmic reticulum (ER)-derived protein bodies. The absence of lysine in all zein polypeptides results in an imbalance in the amino acid composition of maize seeds. We modified the maize γ-zein gene through the introduction of lysine-rich (Pro-Lys)n coding sequences at different sites of the γ-zein coding sequence. Maize endosperms were transiently transformed by biolistic bombardment with Lys-rich γ-zein constructs under the control of the 1.7 kb γ-zein seed-specific promoter and the cauliflower mosaic virus (CaMV) 35S promoter. When (Pro-Lys)n sequences were inserted contiguous to or in substitution of the Pro-Xaa region of the γ-zein, high levels of protein were observed. In contrast, when (Pro-Lys)n sequences were inserted five residues from the C-terminal, the transcript was present but modified protein was not detected. These results suggest that only an appropriate positioning of Lys-rich inserts leads to the modified molecule displaying correct folding and stability. Subcellular localization analyses and immunoelectron microscopy studies on isolated protein bodies demonstrated that modified γ-zeins accumulate within these organelles and co-localized with endogenous - and γ-zeins. The studies reported here show the feasibility of manipulating the γ-zein gene in order to obtain stable and correctly targeted Lys-rich zeins in maize seeds.

endosperm-specific expression lysine-rich γ-zein maize endosperm transient transformation γ-zein gene 

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Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Margarita Torrent
    • 1
  • Iñaki Alvarez
    • 1
  • M. Isabel Geli
    • 1
    • 2
  • Ionara Dalcol
    • 3
  • Dolors Ludevid
    • 1
  1. 1.Departament de Genètica MolecularCentre d'Investigació i Desenvolupament, (CSIC)BarcelonaSpain
  2. 2.Department of Biochemistry, BiozentrumUniversity of BaselBaselSwitzerland
  3. 3.Departament de Quimica OrgànicaUniversitat de BarcelonaBarcelonaSpain

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