Fig. 1

The relative expression of bitter acid biosynthesis genes A: HlBCAT1, B: HlVPS, C: HlPT1L, D: HlPT2, E: HlHS1 and F: HlHS2 (see Table 1) relative to reference genes in different tissues of aromatic and bitter hop cultivars. Tissues: A – apex, B – leaf, C – bract without lupulin, D – flower, E – young cone, and F – lupulin gland. Significant t-test group differences at the following probability levels: * - P < 0,1, ** - P < 0,05, and *** - P < 0,01. straight line - median, dashed line – average, and box – 95% percentile ± standard deviation