Molecular mechanisms of auxin-mediated plant development

 描述（申请人提供）：生长素是植物生长发育的许多方面所必需的激素。这个建议的总体目标是阐明生长素调节各种发育过程的分子机制。我们通过阐明生长素生物合成的分子机制来探讨生长素生物学中的关键问题。我们已经明确建立了第一个完整的色氨酸（Trp）依赖的生长素生物合成途径。植物使用两步途径将Trp转化为吲哚-3-乙酸（IAA），这是植物中主要的生长素。Trp首先被氨基转移酶的TAA家族转化为吲哚-3-丙酮酸（IPA），随后IPA被含黄素的单加氧酶的YUC家族转化为IAA。TAA/YUC途径是植物生长素生物合成的主要途径。通过筛选生长素生物合成突变体的遗传修饰因子，我们牢固地建立了一个新的信号转导途径生长素介导的器官发生。信号通路中的已知组分是：蛋白激酶PID、支架蛋白NPY 1和转录因子ARF 5。我们在生长素生物合成方面的进展使我们能够通过时空控制来调节植物中的生长素水平，从而使我们能够从不同的角度解决生长素生物学中的关键问题。本研究的主要目的是：（1）评估生长素的局部生物合成和极性运输对植物生长的相对贡献， 拟南芥根的发育;（2）阐明蛋白激酶SKA 1在生长素介导的器官发生中的作用;（3）从遗传学角度阐明生长素调控花发育的信号通路。拟议的实验将导致一个更完整的图片本地生长素生物合成在植物发育中的作用。拟议的工作还将为控制复杂发育过程的信号机制提供重要的新见解。

 DESCRIPTION (provided by applicant): Auxin is an essential hormone for many aspects of plant growth and development. The general goal of this proposal is to elucidate the molecular mechanisms by which auxin regulates various developmental processes. We approached key questions in auxin biology by first elucidating the molecular mechanisms of auxin biosynthesis. We have unambiguously established the first complete tryptophan (Trp)-dependent auxin biosynthesis pathway. Plants use a two-step pathway to convert Trp into Indole-3-acetic acid (IAA), the main auxin in plants. Trp is first converted to indole-3-pyruvate (IPA) by the TAA family of amino transferases and subsequently, IPA is converted to IAA by the YUC family of flavin-containing monooxygenases. The TAA/YUC pathway is the major auxin biosynthesis pathway in plants. By screening for genetic modifiers of auxin biosynthesis mutants, we firmly established a novel signal transduction pathway for auxin-mediated organogenesis. The known components in the signaling pathway are: the protein kinase PID, the scaffolding protein NPY1, and the transcription factor ARF5. Our progress in auxin biosynthesis enables us to modulate auxin levels in plants with spatial and temporal control, thus allowing us to address key questions in auxin biology from a different perspective. The main aims of the proposed studies are: (1) Assess the relative contributions of local auxin biosynthesis and polar auxin transport to Arabidopsis root development; (2) Elucidate the roles of the protein kinase SKA1 in auxin-mediated organogenesis; (3) Genetically delineate the signaling pathway by which auxin controls flower development. The proposed experiments will lead to a more complete picture of the roles of localized auxin biosynthesis in plant development. The proposed work will also provide significant new insights into the signaling mechanisms that control complex developmental processes.