Abstract
The natural auxin IAA (indole-3-acetic acid) is one of very precisely studied subjects, and its biosynthesis mechanism has been also well investigated. However, since the biosynthesis system consists of several pathways and genes playing a role in those pathways are not fully identified, the biosynthesis mechanism of IAA remains to be elucidated more precisely. Chemical genetics approach with biosynthesis inhibitors is a reliable means for studies of hormone biosynthesis. However, biosynthesis inhibitors for IAA had not been available. Recently, we reported the inhibitory activity of L-2-aminooxy-3-phenylpropionic acid (L-AOPP) to IAA biosynthesis in Arabidopsis, although its specificity to the activity remained to be shown. In this study, we demonstrated biochemical study for the inhibitory activity of L-AOPP to TAA1 (TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1), which has been reported to be an IAA biosynthesis enzyme. Furthermore, physiological effects of L-AOPP were examined, and its mode of action was analyzed.
