The tobacco bZIP transcription factor BZI-1 binds to G-box elements in the promoters of phenylpropanoid pathway genes in vitro, but it is not involved in their regulation in vivo.

摘要: Screening of a tobacco (Nicotiana tabacum) cDNA library resulted in the isolation clone encoding bZIP transcription factor BZI-1. With respect to amino acid sequence, conservation protein domains, genomic exon-intron structure and expression pattern, BZI-1 is closely related CPRF2, OHP1/2, BLZ1 REB, group proteins which have been described number dicot monocot species. exhibits characteristics factor. It binds G-box C-box cis-elements vitro, it localised nucleus, N-terminal region functions as an activation domain both yeast plant cells. Since BZI-1-related factors isolated from dicots by vitro binding elements chalcone synthase (CHS) promoter, has suggested that phenylpropanoid pathway genes, such CHS PAL (phenylalanine ammonia-lyase), are targets these vivo. However, after infection with Pseudomonas syringae or Tobacco Mosaic Virus, no changes pathogen-induced were observed transgenic plants expressing increased levels dominant negative form protein, BZI-1-ΔN. In contrast tissue-specific PAL, was found be ubiquitously expressed plants. Furthermore, for Expression VP16-BZI-1 fusion would expected result constitutive target genes. tetracycline-dependent did not PAL. On basis data, we conclude genes analysed Thus, pattern DNA need always reflect their vivo function.