Expression of the Brazil nut methionine-rich protein and mutants with increased methionine in transgenic potato

Authors: Tu H.M.¹; Godfrey L.W.¹; Sun S.S.M.^{1, 2}

Source: Plant Molecular Biology, Volume 37, Number 5, July 1998 , pp. 829-838(10)

Publisher: Springer

Abstract:

A cDNA encoding the methionine-rich (19 mol% Met) protein in Brazil nut was placed under the regulation of CaMV 35S promoter and nopaline synthase terminator and introduced into the potato cultivar Russet Burbank via Agrobacterium-mediated transformation. To further enhance the Met content in the transgenic plants, chimeric genes containing four mutant constructs, BoxIa (with 5 additional Met), BoxIIa (2 additional Met), BoxIaIIa (7 additional Met), and BoxIIa^2 (7 additional Met), were also generated by sequence modifications of the cDNA and transferred into potato. Analysis of the microtubers and leaves of the transgenic potato plants revealed, in general, with the exception of the BoxIIa^2, the presence of mRNA transcripts of the expected size and the correctly processed Met-rich 9 kDa subunit polypeptides. The expression levels in the leaves among the various constructs and individual transgenic plants varied between <0.01% and 0.2% of total protein. The corresponding expression in the tubers was usually 2- to 4-fold lower than in leaves. In the case of BoxIIa^2, which contains two tandem repeats of the BoxIIa mutant sequence, a larger (10.5–11 kDa) polypeptide was detected. These findings demonstrated that it is feasible to exploit the variable region of the Brazil Nut 2S protein for enhanced Met contents and perhaps for other desirable properties.

Keywords: Brazil nut 2S protein; potato; methionine; expression; tubers; transgenic plants

Language: English

Document Type: Regular paper

Affiliations: 1: Department of Plant Molecular Physiology, University of Hawaii, Honolulu, HI 96822, USA 2: Department of Biology, Chinese University of Hong Kong, Shatin, NT, Hong Kong

Publication date: 1998-07-01

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• In this Subject: Biology ,  Botany ,  Organic Chemistry ,  Genetics
• By this author: Tu H.M. ;  Godfrey L.W. ;  Sun S.S.M.

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