To construct the Gal4 DBD-NINJA plasmid, the Arabidopsis NINJA full-length coding sequence was polymerase chain reaction (PCR)–amplified, digested, and ligated into the Gal4 plasmid pM (Clontech). To generate VP16 fusion constructs, full-length and truncated coding sequences of rice TPR2, TPR1, and TPL were PCR-amplified from pLexA-N fusion plasmids (13 (link)), digested, and inserted into the pVP16 plasmid (Clontech). The reporter plasmid pG5-Luc contains a luciferase gene under the control of a Gal4 upstream activating sequence element. Gal4 fusion constructs (30 ng) were cotransfected with VP16 fusion constructs (30 ng), together with 100 ng of pG5-Luc and 1 to 3 ng of phRG-TK/Renilla (Promega), into AD293 cells in 24-well plates by Lipofectamine (Invitrogen) method according to the manufacturer’s manual. Cells were harvested 17 hours after transfection with 1× Passive Lysis Buffer (Promega). Luciferase/Renilla activities were measured with the Dual-Luciferase Kit (Promega), and data were plotted as firefly luciferase activity relative to Renilla luciferase activity.