解析林木重要代谢途径，揭示代谢反应关键基因和基因家族的功能，是后基因组时代林木遗传学的核心任务之一。本课题以林木模式物种杨树为材料，以赤霉素代谢途径为研究对象，从比较基因组→基因表达→蛋白质结构与功能→体内生理功能四个层次，解析杨树赤霉素代谢途径，揭示每一步代谢反应的关键基因，阐明杨树赤霉素代谢相关基因家族的功能分化机制，为林木遗传改良提供新的理论依据和候选基因资源，具有重要的理论意义和实践价值。

Exploration of key metabolic pathways of forest trees, and identification of the key genes and gene families in metabolic pathways, is one of the central tasks of tree genetics in post-genomic era. Gibberellins are key plant hormones that are biosynthesized through complex pathways and control diverse aspects of growth and development. In this study, we will focus on Populus gibberellin metabolic pathway. Firstly, we will identify the candidate genes involved in Populus gibberellin metabolic pathway using the methods of comparative genomics and molecular systematics. Secondly, the expression pattern of the candidate genes in Populus under normal and stress conditions will be examined using RT-PCR and real time RT-PCR. Thirdly, we will clone all the candidate genes from Populus genomes, express proteins in vitro, and purify the proteins. The biochemical function of the recombinant proteins will be analyzed in detail. Finally, we will investigate the physiological functions of the Populus candidate genes in vivo by transgenic Arabidopsis mutants. In a word, by integrating all the results about molecular evolution, gene expressions and protein functions, this study will identify the key genes in Populus gibberellin metabolic pathway, and shed light on the functional divergence of gene families.