Development of New Genetic Resources for Auxin Biology

During the last 60 years, physiological studies have implicated the plant hormone indole-3-acetic acid (IAA or auxin) in the regulation of virtually every aspect of plant development. Auxin is synthesized in meristems and young organs, transported through the plant by a dedicated transport system and ultimately produces a specific cellular response. Since the hormone functions in all higher plant species, a thorough understanding of auxin homeostasis and response will impact all aspects of agriculture. Qualities such as stature, shoot and root architecture, shoot strength, seed and fruit size, fruit ripening, and the senescence program are all regulated in part by auxin and may be targets for directed engineering. Previous studies have demonstrated a high level of genetic and biochemical redundancy in most areas of auxin biology. For this reason it is important to study a model plant system such as Arabidopsis that is amenable to high-throughput biochemical and molecular genetic techniques.

This 'proof of concept' award will support an integrated analysis of auxin biology that will include biochemical, genetic, and molecular strategies. The primary goal of the project is to develop novel high throughput genetic screens for genes that function in auxin homeostasis, transport, and response. Three screens will be conducted.

1) Improved analytical techniques will be utilized together with robotic systems, to screen large numbers of chemically mutagenized Arabidopsis seedlings for changes in IAA levels.

2) Large-scale activation-tagging screens for mutants affected in all aspects of auxin biology will be conducted.

3) A functional screen for genes involved in auxin metabolism will be conducted in E. coli cells.

These screens are broad and are expected to recover a diverse collection of mutants. The mutants will be subjected to detailed biochemical analysis of auxin metabolism and response and molecular studies of gene function. The results of the project will establish the groundwork for a comprehensive functional genomics study of auxin biology.