Overexpression of ΔEmBP, a truncated dominant negative version of the wheat G-box binding protein EmBP-1, alters vegetative development in transgenic tobacco

Nancy A. Eckardt, Lauren McHenry, Mark J. Guiltinan

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7 Scopus citations

Abstract

As a first step toward elucidating the in vivo function of plant bZIP proteins and their related G-box cis elements, we have introduced a dominant negative inhibitor of G-box-dependent transcriptional activation into tobacco plants by transforming them with a truncated EmBP-1 gene (ΔEmBP) containing the DNA binding and dimerization domains under the control of the CaMV 35S promoter. Five independent lines of transgenic plants expressing ΔEmBP were identified, as demonstrated by immunodetection of the transgenic protein in leaf extracts, and the ability of the protein to bind a target G-box DNA sequence. The transgenic plants exhibited an abnormal phenotype characterized by interveinal chlorosis, growth inhibition and weakening of stems and petioles, the severity of which positively correlated with ΔEmBP expression and G-box DNA binding capability. Furthermore, development of chlorosis and growth inhibition was dependent on growth irradiance. Low light promoted the development of interveinal chlorosis and growth inhibition in the transgenic plants, whereas high light conditions led to near-complete amelioration of the abnormal phenotype. Transgenic plants under both light regimes showed signs of impaired stem and petiole function which was not observed in wild-type tobacco. RbcS gene expression was not significantly altered by ΔEmBP expression, suggesting that down-regulation of this gene was not responsible for the altered phenotype. The results suggest that G-box elements specific for the EmBP-1 class of bZIP proteins have an important developmental function in vegetative plant tissues, and that the trans-dominant negative mutant approach is a useful tool for continued in vivo functional analysis of bZIP transcription factors and their corresponding cis elements in plants.

Original languageEnglish (US)
Pages (from-to)539-549
Number of pages11
JournalPlant molecular biology
Volume38
Issue number4
DOIs
StatePublished - Jan 1 1998

All Science Journal Classification (ASJC) codes

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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