Plant Molecular Biology

, Volume 23, Issue 1, pp 1–9 | Cite as

Down-regulation of two non-homologous endogenous tomato genes with a single chimaeric sense gene construct

  • G. B. Seymour
  • R. G. Fray
  • P. Hill
  • G. A. Tucker
Research Article


Tomatoes (Lycopersicon esculentum Mill cv. Ailsa Craig) were transformed with a gene construct having 244 bp of the 5′ end of a polygalacturonase (PG) cDNA, coding for a 71 amino acid N-terminal extension to the mature protein, fused to 1320 bp of a pectinesterase (PE) cDNA encoding the full sequence of the mature PE protein. This chimaeric gene was inserted in a sense orientation between a CaMV 35S promoter and terminator for constitutive expression. In transformed tomato plants expression of the endogenous PG and PE genes in the fruit was inhibited; there was little or no observable PG and PE mRNA and a substantial reduction in the level of PG and PE enzyme activity. The transgene was expressed in the leaves of the transformed plants as demonstrated by the accumulation of mRNA, but no protein product could be identified. However, no transgene mRNA or protein were observed in the transgenic fruit.

This paper represents the first report of the down-regulation of two non-homologous endogenous genes using a single gene construct. A sense gene construct was responsible for these effects. These findings are discussed in relation to possible mechanisms of action of co-suppression.

Key words

down-regulation gene expression polygalacturonase pectinesterase chimaeric sense gene transgenic co-suppression 


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Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • G. B. Seymour
    • 1
  • R. G. Fray
    • 2
  • P. Hill
    • 1
  • G. A. Tucker
    • 1
  1. 1.Department of Applied BiochemistryUniversity of Nottingham, School of AgricultureLoughboroughUK
  2. 2.AFRC Research Group in Plant Gene RegulationUniversity of Nottingham, School of AgricultureLoughboroughUK

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