Functional characterization of PvKSL13 and PvKSL15 as ent-kaurene synthases. GC-MS extracted ion chromatograms (EIC; m/z 257) are shown for reaction products obtained from E. coli coexpression assays of the class I diTPSs PvKSL13 and PvKSL15 with select class II diTPSs: ent-CPS ZmAn2 (Harris et al., 2005), (+)-CPS AgAS:D621A (Peters and Croteau, 2002), and syn-CPS PvCPS8. Numbered peaks are as follows: 1, ent-copalol (i.e. dephosphorylated ent-CPP); 2, unidentified diterpene; 3, ent-kaurene; 9, syn-copalol; 15, (+)-copalol; 23, unidentified diterpene.