From tRNA modification to cytokinins - Characterisation of tRNA-mediated cytokinin biosynthesis in the early land plant Physcomitrella

从 tRNA 修饰到细胞分裂素 - 早期陆地植物立碗藓中 tRNA 介导的细胞分裂素生物合成的表征

• 批准号: 73316273
• 负责人: Privatdozent Dr. Klaus von Schwartzenberg
• 金额: --
• 依托单位: Biozentrum Klein Flottbek und Botanischer Garten
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/73316273?language=en
• 关键词: tRNA; modification; cytokinins; Characterisation; mediated

For the moss Physcomitrella patens we collected evidence suggesting that in this model organism the plant hormones cytokinins (isopentenyl-derivatives of adenine), in contrast to seed plants, originate exclusively from tRNA. We therefore assume that in early steps of land plant evolution the isopentenylation of tRNA, catalysed by tRNA-isopentenyltransfrases (tRNA-IPTs), took over the function of providing precursors for free cytokinins acting as plant hormones. This tRNA-IPT mediated pathway of cytokinin biosynthesis was preserved during the evolution of seed plants, however seed plants additionally developed the de novo synthesis of free cytokinins via isopentenylation of the adenylates ADP/ATP. The proposed project aims (1) to establish the unequivocal proof for the exclusivity of the tRNA-dependent pathway of cytokinin biosynthesis in moss, (2) to provide basic information on the regulation of the tRNAdependent cytokinin biosynthesis on the levels of gene regulation as well as tRNA-IPT properties and substrate availability. The aims will be achieved by the generation of tRNA-IPT gene knockout plants and tRNA-IPT overexpressors. Transcriptional studies will correlate the localisation of tRNA-IPT expression with the topology of cytokinin biosynthesis/activity. A detailed description of transcription and adenine37- isopentenylation of tRNAs will help to understand the mode of function of tRNA-mediated cytokinin biosynthesis, contributing to growth control also in seed plants.

对于苔藓小立碗藓，我们收集的证据表明，在这种模式生物的植物激素细胞分裂素（异戊烯基衍生物的腺嘌呤），与种子植物，完全来自tRNA。因此，我们假设在陆地植物进化的早期阶段，由tRNA-异戊烯基转移酶（tRNA-IPT）催化的tRNA的异戊烯基化，接管了为作为植物激素的游离细胞分裂素提供前体的功能。这种tRNA-IPT介导的细胞分裂素生物合成途径在种子植物的进化过程中被保留下来，然而种子植物还通过腺苷酸ADP/ATP的异戊烯化从头合成游离细胞分裂素。本研究的目的是：（1）为苔藓中依赖于tRNA的细胞分裂素生物合成途径的排他性提供明确的证据;（2）提供有关依赖于tRNA的细胞分裂素生物合成在基因调控水平上的调控以及tRNA-IPT性质和底物可用性的基本信息。这些目标将通过产生tRNA-IPT基因敲除植物和tRNA-IPT过表达子来实现。转录研究将使tRNA-IPT表达的定位与细胞分裂素生物合成/活性的拓扑结构相关。转录和腺嘌呤37-异戊烯化的tRNA的详细描述将有助于了解tRNA介导的细胞分裂素生物合成的功能模式，有助于种子植物的生长控制。