Abstract
Auxin regulates various developmental processes, and its homeostasis is rigorously-controlled. In Zinnia elegans cell cultures, isolated mesophyll cells divides and differentiate into tracheary elements (TEs) in the presence of auxin. In this culture system, auxin transport inhibitors such as NPA prevent TE differentiation and high concentrations of auxin overcome the repression of TE differentiation. We found that NPA increased the amounts of NAA-derivatives and decreased free NAA. This free NAA depletion may prevent TE differentiation and cell division.
In this study, using novel IAA-amino acid synthetase inhibitors, we analyzed the auxin metabolism during TE differentiation. As a result, NPA increased the amounts of IAA-amino acid conjugates and decrease of free IAA. Furthermore, treatment of IAA-amino acid synthetase inhibitors on NPA-treated cells decreased the level of IAA conjugates and also recovered the NPA-suppressed cell division. Based these results, we will discuss the auxin metabolism in association with cell division and differentiation.
