Abstract
We reported that L-aminooxy-phenylpropionic acid (AOPP) inhibits indole-3-acetic acid (IAA) biosynthesis. Since AOPP is unstable in MS medium and has side effects, e.g., inhibiting phenylalanine ammonia-lyase (PAL), more stable inhibitor having higher specificity was developed. We have designed and synthesized various compounds structurally related to AOPP. Among these compounds, KOK1169 inhibited a recombinant enzyme of IAA biosynthesis enzyme, TRYPTOPHAN AMINOTRANSFERASE of ARABIDOPSIS 1, stronger than AOPP. Furthermore, KOK1169 inhibited recombinant enzyme, AtPAL2 weaker than AOPP. In Arabidopsis seedlings, treatment with KOK1169 at 30 μM for 3 h was as effective as that with AOPP to reduce endogenous IAA. However KOK1169 inhibited the seedling growth for 8 days, while AOPP did not. The seedling growth was recovered to the control level with exogenous IAA treatment. These results suggested that KOK1169 has higher specificity as an auxin-biosynthesis inhibitor than AOPP. This work was supported by the Program for Promotion of Basic and Applied Researches for Innovations in Bio-oriented Industry (BRAIN).
