Control of polar plant cell growth: functional characterization of regulators and effectors of the tobacco pollen tube Rac/Rop GTPase Nit-Rac5

极性植物细胞生长的控制：烟草花粉管 Rac/Rop GTPase Nit-Rac5 调节子和效应子的功能表征

• 批准号: 5456699
• 负责人: Professor Dr. Benedikt Kost
• 金额: --
• 依托单位: Department Biologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5456699?language=en
• 关键词: Control; polar; plant; cell; growth

The goal of the proposed study is to elucidate molecular mechanisms regulating polar pollen tube growth by controlling localized Rac/Rop activation at the tip of these cells, or cellular processes downstream of this event. Results obtained will enhance current knowledge concerning Rac/Rop signaling, and the molecular control of polar plant cell growth, of plant development and of the direction of pollen tube growth during fertilization. Pollen tubes are large cells that grow rapidly in a strictly polar manner through female flower tissue and transport sperm cells enclosed in their cytoplasm to egg cells during fertilization. Tobacco pollen tubes are an excellent model system to investigate polar plant cell growth, because they elongate normally in culture, are amenable to experimental manipulation, can be grown in vitro in large quantities and are genetically tractable (transient and stable transformation, ongoing genome sequencing project). Our published work has shown that Rac/Rop GTPases, plant relatives of Rho family GTPases with apparently diverse and largely uncharacterized functions, are associated with the plasma membrane specifically at the tip of pollen tubes and are key regulators of the polar growth of these cells. Here, we propose to functionally characterize using a variety of approaches proteins that show yeast two-hybrid interaction with the tobacco pollen tube Rac/Rop GTPase Nt-Rac5. Substantial preliminary data based on yeast two-hybrid assays, transient over-expression and GFP tagging indicate that these proteins act either as regulators or effectors of Nt-Rac5.

这项研究的目的是通过控制极地花粉管顶端的RAC/Rop的局部激活，或该事件下游的细胞过程，来阐明调节极地花粉管生长的分子机制。所获得的结果将加强关于RAC/ROP信号的现有知识，以及在受精过程中对极地植物细胞生长、植物发育和花粉管生长方向的分子控制。花粉管是一种大细胞，通过雌花组织以严格的极向方式快速生长，并在受精过程中将封闭在细胞质中的精子细胞输送到卵细胞。烟草花粉管是研究极地植物细胞生长的一个很好的模型系统，因为它们在培养中正常伸长，易于实验操作，可以在体外大量生长，并且遗传容易处理(瞬时和稳定转化，正在进行的基因组测序计划)。我们已发表的工作表明，RAC/Rop GTP酶是Rho家族GTP酶的植物近亲，具有明显的多样性和很大程度上的未知功能，与位于花粉管顶端的质膜相关，是这些细胞极地生长的关键调节因子。在这里，我们建议使用各种方法对显示酵母与烟草花粉管RAC/Rop GTPase NT-rac5双杂交相互作用的蛋白质进行功能表征。基于酵母双杂交、瞬时过表达和GFP标记的大量初步数据表明，这些蛋白既可以作为NT-rac5的调节器，也可以作为效应器。