which was modified based on pGreenII 0800-LUC reporter vector (Hellens et al., 2005). GAL4-LUC contains five copies of GAL4 binding element and minimal TATA region of 35S promoter of CauliXower Mosaic Virus (CaMV), and these sequences are located upstream of the LUC. For the assay of MaC2H2s repressing the MaACS1 and MaACO1 promoters, MaC2H2-1/2 were inserted into the pEAQ vector as effector, while the MaACS1 and MaACO1 promoters were cloned into pGreenII 0800-LUC double-reporter vector as reporter. The constructed effector and reporter plasmids were co-transformed into tobacco leaves by Agrobacterium tumefaciens strain GV3101. After two days, LUC and REN luciferase activities were measured using the dual luciferase assay kit (Promega) on the Luminoskan Ascent Microplate Luminometer (Thermo). The results were calculated by the ratio of LUC to REN. At least six biological repeats were assayed for each combination.