Future directions
Regulation of bioactive auxin levels is clearly complex and many questions about auxin biosynthesis and modified auxin forms remain unanswered. Chief among these questions is how the plant integrates and regulates local auxin biosyn- thesis, the generation of storage forms, release from storage forms, and transport to contribute to the generation and maintenance of auxin gradients. Understanding transcrip- tional regulation of auxin biosynthesis genes and the post- translational control of activity may provide some tools to answer these questions.