Auxin and axillary meristem development
Yunde Zhao

Section of Cell and Developmental Biology, University of California San Diego, 9500 Gilman Drive, la Jolla, CA 92093-0116, USA.
Corresponding Author：Tel: 858-822-2670; Fax: 858-534-7108; E-mail: yundezhao@ucsd.edu

Abstract
Auxin is an essential regulator for almost every aspect of plant growth and development.  Disruption of auxin biosynthesis or transport or signaling causes pleiotropic developmental defects. One of the striking phenotypes associated with defective auxin pathways is the development of naked pin-like inflorescences in Arabidopsis and maize. Pin-like mutants fail to develop axillary meristems and flowers, but how auxin controls axillary meristem development and organogenesis is still not well understood. We conducted a genetic screen for mutants with pin-like inflorescences in an auxin biosynthesis mutant background, which presumably provides a more sensitized background for the screening. We previously showed that inactivation of YUC genes, which encode flavin monooxygenases that catalyze a rate-limiting step in auxin biosynthesis, caused defects in cotyledon formation, leaf initiation, and flower development. We isolated a series of yuc1 yuc4 enhancers that develop pin-like inflorescences, but fail to produce flowers. Characterization of the yuc1 yuc4 enhancers has uncovered a novel-signaling pathway responsible for auxin-regulated plant organogenesis.

Key Words: YUC; auxin; growth and development; Arabidopsis