Protein structures of Phalaenopsis NPR1. (A) A schematic representation of PhaNPR1. The three major domains, BTB, ankyrin repeats domains (ANK), and C terminal domain (NPR1_like_C), of this protein are indicated with boxes. The two 21-nt regions indicate the regions used for PhaNPR1 silencing. (B) Alignment of PhaNPR1 (underlined) with NPR1 homologs whose localizations have been determined. AtNPR3, AtNPR4 from Arabidopsis (Liu et al., 2005; Zhang et al., 2006), MhNPR1 from Malus hupehensis (Zhang et al., 2011), GmNPR1-1 from Glycine max (Sandhu et al., 2009), VvNPR1.1 from grapevine (Le Henanff et al., 2011), and NtNPR1 from tobacco (Maier et al., 2010), were localized to the nucleus, while AtNPR1 from Arabidopsis, TcNPR1 from Theobroma cacao (Shi et al., 2010), and OsNPR1/NH1 from rice were localized to the cytoplasm without reductants. The BTB/POZ and ANK domains, and the C-terminal nuclear localization signal (NLS) are indicated with a solid-lined box, underline, and dashed-lined box, respectively. The conserved LENRV motif is indicated with a double line and a NIMIN binding site is labeled with (*). The conserved cysteine residues are indicated with an asterisk (*), and the cysteine residue corresponding to C216 in Arabidopsis, which is important for the redox regulation of NPR1, is indicated with a black triangle.