Fig. 4

Changes in IAA, IAA conjugates, and auxin-related gene expression during the transition from dormancy to germination of white spruce seeds. a IAA and IAA conjugates in seeds as determined by UPLC/ESI-MS/MS during moist-chilling at 3 °C (0, 10, and 21 d) and during germination (6, 24 and 80 h) and seedling growth (9 d). Each data point is the average of two biological replicates. b Schematic characterization of key genes and their interplays in auxin signalling cascade. Connections represent positive (arrow) regulation. c Transcript levels of auxin metabolism genes, auxin signalling genes and selected downstream targets during moist-chilling (0, 10, 21 d), germination (6, 24, 80 h) and seedling growth (9 d) (black bars). Also shown are previously chilled seeds placed in two control treatments - 6 h germination conditions under darkness at either 30 °C (dark grey bar) or 20 °C (light grey bar). Each data point is the average of three biological replicates. Bars indicate the SEM. Notes: 1) see Fig. 2 note for asterisk in c; 2) no other ARF homologs (such as ARF16) and GH3 (converting active IAA to IAA-aa) homologs were found in white spruce by BLASTN