Expression and antisense inhibition of transgenes in Phytophthora infestons is modulated by choice of promoter and position effects

Howard S. Judelson, Robert Dudler, CornéM J. Pieterse, Shiela E. Unkles, Richard W Michelmore

Research output: Contribution to journalArticle

45 Scopus citations


Procedures were identified for manipulating the expression of genes in the oomycete fungus, Phytophthora infestans. The activities of five putative promoter sequences, derived from the 5' regions of oomycete genes, were measured in transient assays performed in protoplasts and in stable transformants. The sequences tested were from the ham34 and hsp70 genes of Bremia lactucae, the actin-encoding genes of P. infestons and P. megaspermaand a polyubiquitin-encoding gene of P. infestans. Experiments using the GUS reporter gene (encoding β-glucuronidase) demonstrated that each 5' fragment had promoter activity, but that their activities varied over a greater than tenfold range. Major variation was revealed in the level of transgene expression in individual transformants containing the same promoter::GUS or promoter::lacZ fusion. The level of expression was not simply related to the number of genes present, suggesting that position effects were also influencing expression. Fusions between the ham34 promoterand full-length and partial GUS genes in the antisense orientation blocked the expression of GUS in protoplasts and in stable transformants.

Original languageEnglish (US)
Pages (from-to)63-69
Number of pages7
Issue number1
StatePublished - Oct 29 1993



  • late blight
  • Oomycetes
  • transformation, fungi
  • β-galactosidase
  • β-glucuronidase

ASJC Scopus subject areas

  • Genetics

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