Auxin is an essential regulator for almost every aspect of plant growth and development. The general goal of this proposal is to elucidate the molecular mechanisms by which auxin regulates plant organogenesis and other developmental processes. During the last grant period, we demonstrated that the YUCCA (YUC) flavin monooxygenases play an essential role in auxin biosynthesis and various developmental processes including embryogenesis, seedling growth, vascular patterning, and floral development. Previous genetic studies on auxin signaling were centered on analysis of mutants resistant to exogenous auxin. Our understanding of auxin biosynthesis allowed us to elucidate the molecular mechanisms of auxin action in plant development from a completely different perspective. We identified npy1 (naked pins in yuc mutants) from a genetic screen for enhancers of the yuc1 yuc4 double mutants that are partially auxin deficient. The npy1 yuc1 yuc4 triple mutants developed pin-like inflorescences and failed to form any flowers, a hallmark phenotype caused by defects in auxin pathways. NPY1 belongs to a large family and is homologous to non-phototropic hypocotyl 3 (NPH3), a BTB protein regulating phototropism along with the AGC kinase PHOT1. NPY1 works with PID, a PHOT1 homolog, to regulate auxin-mediated organogenesis using a mechanism analogous to that used by NPH3/PHOT1 in phototropism. The findings put yuc, npy1, and known auxin mutants pin1, pid, and mp in a genetic framework for further understanding of the mechanisms governing auxin-regulated plant development. The findings also reveal a novel mechanism for AGC kinase-mediated signal transduction in plants. The primary aims of the proposed studies are (1) Analysis of the mechanisms of YUC genes in auxin biosynthesis and plant development;(2) Elucidation of the biochemical mechanisms of NPY1 in auxin-regulated organogenesis;(3) Determination of the unique and overlapping functions of the NPY1 family genes in auxin-regulated plant development;(4) Genetic dissection of the mechanisms by which auxin regulates plant development. The proposed experiments will provide significant new insight into the molecular mechanisms of auxin action in plant development, particularly in organogenesis. A clear understanding of the mechanisms by which auxin regulates complex developmental processes is of fundamental importance to plant biology and will have a significant agricultural impact. The proposed study will also extend our understanding of signaling mechanisms controlling complex developmental processes in other eukaryotes, particularly the mechanisms of AGC kinases, which have been implicated in diverse developmental programs in other organisms including humans.

Public Health Relevance

The proposed research is aimed to elucidate the molecular mechanisms by which auxin controls the formation of plant organs. The proposed research will augment our understanding of complex signal transduction mechanisms governing organogenesis and other developmental processes in eukaryotes including humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM068631-09
Application #
8247108
Study Section
Development - 1 Study Section (DEV1)
Program Officer
Maas, Stefan
Project Start
2003-07-01
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2014-02-28
Support Year
9
Fiscal Year
2012
Total Cost
$314,310
Indirect Cost
$106,529
Name
University of California San Diego
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Chen, Qingguo; Dai, Xinhua; De-Paoli, Henrique et al. (2014) Auxin overproduction in shoots cannot rescue auxin deficiencies in Arabidopsis roots. Plant Cell Physiol 55:1072-9
Gao, Yangbin; Zhao, Yunde (2014) Self-processing of ribozyme-flanked RNAs into guide RNAs in vitro and in vivo for CRISPR-mediated genome editing. J Integr Plant Biol 56:343-9
Gao, Yangbin; Zhao, Yunde (2013) Epigenetic suppression of T-DNA insertion mutants in Arabidopsis. Mol Plant 6:539-45
Hentrich, Mathias; Bottcher, Christine; Duchting, Petra et al. (2013) The jasmonic acid signaling pathway is linked to auxin homeostasis through the modulation of YUCCA8 and YUCCA9 gene expression. Plant J 74:626-37
Dai, Xinhua; Mashiguchi, Kiyoshi; Chen, Qingguo et al. (2013) The biochemical mechanism of auxin biosynthesis by an arabidopsis YUCCA flavin-containing monooxygenase. J Biol Chem 288:1448-57
Zhao, Yunde (2012) Auxin biosynthesis: a simple two-step pathway converts tryptophan to indole-3-acetic acid in plants. Mol Plant 5:334-8
Won, Christina; Shen, Xiangling; Mashiguchi, Kiyoshi et al. (2011) Conversion of tryptophan to indole-3-acetic acid by TRYPTOPHAN AMINOTRANSFERASES OF ARABIDOPSIS and YUCCAs in Arabidopsis. Proc Natl Acad Sci U S A 108:18518-23
Mashiguchi, Kiyoshi; Tanaka, Keita; Sakai, Tatsuya et al. (2011) The main auxin biosynthesis pathway in Arabidopsis. Proc Natl Acad Sci U S A 108:18512-7
Hou, Xianhui; Liu, Sainan; Pierri, Florencia et al. (2011) Allelic analyses of the Arabidopsis YUC1 locus reveal residues and domains essential for the functions of YUC family of flavin monooxygenases. J Integr Plant Biol 53:54-62
Li, Yuanting; Dai, Xinhua; Cheng, Youfa et al. (2011) NPY genes play an essential role in root gravitropic responses in Arabidopsis. Mol Plant 4:171-9

Showing the most recent 10 out of 27 publications