Acyl donor specificities of SATs and AATs. (A) Chemical structures of acyl donors used in the enzyme assays: acetyl-CoA (Ac), isobutyryl-CoA (Ib), isovaleryl-CoA (Iv) and methylcrotonyl-CoA (Mc). Acyltransferase activities of (B) LeSAT1, (C) EpSAT1-1, (D) EpSAT1-2, (E) LeSAT2, (F) EpSAT2-1, (G) EpSAT2-2, (H) AeSAT2, (I) LeAAT1, (J) EpAAT1-1, (K) EpAAT1-2, (L) AeAAT1, (M) SoAAT1, (N) LeAAT2, (O) EpAAT2-1, (P) EpAAT2-2, (Q) EpAAT2-3 and (R) AeAAT2 determined using four acyl donors and either shikonin or alkannin as an acyl acceptor. The amounts of various shikonin/alkannin derivatives produced per reaction time and enzyme content were compared. N.D., not detected; trace, trace amounts detected. Significant differences (P < 0.05) of means ± standard error (n = 3) were determined using the Turkey–Kramer test and are indicated by different lowercase letters.