The cDNA of the cis-acting CChMVd-HHR was PCR-amplified with Taq DNA polymerase as described in Ztouti et al. [23] using 5′-GTCGGCACCTGACGTCGGTGTCCTGATGAAGATCCATGAGAGGATCGAAACCTCTTCTAG-3′ as template, and 5′-TAATACGACTCACTATAGGAAGAGGTCGGCACCTGACGTCGG-3′ containing the T7 RNA polymerase promoter(underlined), as sense primer and 5′-CTAGAAGAGGTTTCGATCCTCTC-3′ as antisense primer.