Figure 4
From: Isolation of a strong Arabidopsis guard cell promoter and its potential as a research tool
Serial deletion of the pGC1 promoter defines regions for guard cell expression. A. Representative T1 plants from different promoter::GUS transgenic lines. The pGC1(D1) (-1140/+23) promoter mediated stronger GUS expression in guard cells than the original full-length promoter (FL) (-1693/+23). GUS expression of pGC1(D2)::GUS and pGC1(D3)::GUS was weaker than that of the pGC1(FL)::GUS and pGC1(D1)::GUS. The shortest promoter pGC1(D4) (-224/+23) drives reporter expression in tissues and cells besides guard cells. B. Serial deletion of the pGC1 promoter defines regions for guard cell expression. The black arrowheads stand for TAAAG elements while the smaller gray arrowheads stand for AAAAG elements. Arrowheads on the top of the promoter line are on the sense strand while arrowheads below the promoter line are on the antisense strand. The central TAAAG on the sense strand was also marked by a star and was chosen for block mutagenesis. The region from -1693 to -1140 contains repressor elements for guard cell expression and the region from -1140 to -224 contains elements for guard cell specificity and also enhancer elements for guard cells expression.