Expression patterns of SmDXS genes and the phylogenetic relationship of their deduced proteins with various other plant species. (A) Phylogenetic relationship of plant DXSs. The rooted Neighbor–Joining tree was constructed using the MEGA program (version 4.0) with default parameters. CrDXS (Chlamydomonas reinhardtii, CAA07554) was used as an outgroup. Transit peptides of DXSs were trimmed for the analysis of sequence data. DXSs included are Arabidopsis thaliana AtDXS1 (At4g15560), AtDXS2 (At3g21500), AtDXS3 (At5g11380), Oryza sativa OsDXS1 (NP_001055524), OsDXS2 (NP_001059086), OsDXS3 (BAA83576), Populus trichocarpa PtDXS1 (XP_002312717), PtDXS2A (XP_002303416), PtDXS2B (XP_002331678), PtDXS3 (XP_002308644), Picea abies PaDXS1 (ABS50518), PaDXS2A (ABS50519), PaDXS2B (ABS50520), and five S. miltiorrhiza SmDXSs (highlighted). (B) Fold changes of SmDXS genes in flowers (Fl), leaves (Le), stems (St), root cortices (Rc), and root steles (Rs) of S. miltiorrhiza plants grown in soil. The expression level of SmDXS1 in root steles was arbitrarily set to 1. (C) Fold changes of SmDXS genes in leaves (L) and roots (R) of S. miltiorrhiza plantlets treated with MeJA for 0 h and 24 h. The level of SmDXS1 in roots of plantlets without treatment was arbitrarily set to 1.