Gene expression of TcNPR1 and AtPR1 in transgenic Arabidopsis npr1-2 lines. Semi-quantitative RT-PCR was performed with cDNA prepared from the leaves of 4-week-old plants of wild type (C), npr1-2 (n) and 5 independent transgenic npr1-2 mutant lines overexpressing TcNPR1 (1-5). TcNPR1 and AtPR1 expression were evaluated 24 hrs after 1 mM SA treatment. Water-treated control leaves (left panel) from each genotype were also analyzed. Arabidopsis Ubiquitin (AtUbiquitin) expression was assayed as a non SA-induced, cDNA loading control.