Development of New Genetic Resources for Auxin Biology

在过去的60年里，生理学研究表明植物激素吲哚-3-乙酸（IAA或生长素）在植物发育的几乎每个方面都有调控作用。生长素在分生组织和年轻器官中合成，通过专门的运输系统在植物中运输，最终产生特定的细胞反应。由于这种激素在所有高等植物物种中都有作用，因此深入了解生长素的动态平衡及其反应将影响农业的各个方面。植物的身材、茎和根的结构、茎的强度、种子和果实的大小、果实的成熟和衰老等性状都部分受生长素的调控，并可能成为定向工程的目标。以往的研究表明，在生长素生物学的大多数领域，遗传和生化的冗余程度很高。因此，研究像拟南芥这样适合高通量生化和分子遗传技术的模式植物系统是很重要的。这个“概念验证”奖将支持生长素生物学的综合分析，包括生化、遗传和分子策略。该项目的主要目标是开发新的高通量基因筛选在生长素稳态、运输和反应中起作用的基因。将进行三次筛选。1)改进的分析技术将与机器人系统一起用于筛选大量化学诱变的拟南芥幼苗，以了解IAA水平的变化。2)对生长素生物学各方面受影响的突变体进行大规模激活标记筛选。3)在大肠杆菌细胞中进行生长素代谢相关基因的功能筛选。这些筛选范围很广，有望恢复多种多样的突变体。这些突变体将接受生长素代谢和反应的详细生化分析以及基因功能的分子研究。该项目的结果将为生长素生物学的全面功能基因组学研究奠定基础。

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.