Expression patterns of three different PR-1 genes from apple during flower development, and in several cultivars. Two micrograms of total RNA was reverse-transcribed in a 20 μl reaction volume. Two μl of the resulting cDNA template from blossoms of cultivars Gala and Red Delicious at stages; tight-cluster (TC), pink (P), full-bloom (F) and 6 days post full-bloom (+6) or from shoots of the cultivars Jonagold (J), Gala (G), Mutsu (M), Rogers Mac (RM), Red Delicious (RD) and Liberty (L) were used in PCR with primers for PR-1a, PR-1b or PR-1c for 45 cycles. Ten μl of 25 μl reaction mixtures were loaded for each sample. For the EF1α control, 2 μl of the same cDNA template were amplified for 30 cycles with primers for EF1α. Ten μl of 25 μl reaction mixtures were loaded for each sample. Genomic DNA from cultivar Gala was used as the positive PCR control (+). The negative control (-) did not contain template. Note that the EF1α primers span an intron.