TY - JOUR
T1 - Overexpression of ΔEmBP, a truncated dominant negative version of the wheat G-box binding protein EmBP-1, alters vegetative development in transgenic tobacco
AU - Eckardt, Nancy A.
AU - McHenry, Lauren
AU - Guiltinan, Mark J.
PY - 1998/1/1
Y1 - 1998/1/1
N2 - 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.
AB - 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.
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U2 - 10.1023/A:1006081009173
DO - 10.1023/A:1006081009173
M3 - Article
C2 - 9747800
AN - SCOPUS:0031594889
VL - 38
SP - 539
EP - 549
JO - Plant Molecular Biology
JF - Plant Molecular Biology
SN - 0167-4412
IS - 4
ER -