After 10 min at 65 8C, the reaction was transferred to 4 8C and the volume was brought up to 29 ml with 1/ first-strand buffer (GibcoBRL), 1.3 mM dNTP, 6.6 mM DTT and DEPC-treated dd H2O. After 3 min at 42 8C, 200 units of MMLV-RT (GibcoBRL) were added and the reaction was incubated for 1 h at 42 8C. The RT product served as a template in a PCR reaction that was carried out with two custom primers taken from rose dfr cDNA [16].