Phosphate Transport in the Arbuscular Mycorrhizal Symbiosis: Functional Analysis of a Medicago Truncatula Mycorrhiza-Specific Phosphate Transporter

丛枝菌根共生中的磷酸盐转运：蒺藜苜蓿菌根特异性磷酸盐转运蛋白的功能分析

• 批准号: 0343975
• 负责人: Maria Harrison
• 金额: --
• 依托单位: Boyce Thompson Institute Plant Research
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0343975&HistoricalAwards=false
• 关键词: Phosphate; Transport; Arbuscular; Mycorrhizal; Symbiosis

IBN: 0343975AbstractIn natural ecosystems, most vascular flowering plants live in symbiosis with arbuscular mycorrhizal (AM) fungi. These mutually beneficial associations develop in the root system, where the fungus colonizes the root cells to obtain carbon from the plant, while assisting the plant with the acquisition of mineral nutrients, particularly phosphorus, from the soil. Arbuscular mycorrhizal symbioses are formed by almost all vascular flowering plant species and play a significant role in ecosystem biodiversity and functioning. The underlying mechanisms are not yet understood, but the contribution of AM fungi to plant phosphorus nutrition, and the resulting impact on plant health, is clearly a major contributing factor. The overall objectives of this project are to dissect the mechanisms via which the plant obtains phosphate from the fungus in an arbuscular mycorrhizal symbiosis. A model legume, Medicago truncatula, will be used for these analyses. The arbuscular mycorrhizal symbiosis is a highly co-evolved partnership, in which the differentiation of both symbionts results in specialized symbiotic interfaces that enable the exchange of carbon and phosphate. Within the root cells, the fungus forms highly branched hyphae, called arbuscules, which are enveloped in a specialized plant membrane, the peri-arbuscular membrane. Previous studies led to the identification of a unique phosphate transporter (MtPT4) from Medicago truncatula that is located exclusively in the peri-arbuscular membrane. Current objectives are to evaluate motifs implicated in targeting MtPT4 to the peri-arbuscular membrane and to determine the role of MtPT4 in phosphate transport in the symbiosis. Using transgenic lines in which MtPT4 expression is disrupted, or loss-of-function alleles of MtPT4 obtained via TILLING, the hypothesis that MtPT4 is essential for the acquisition of phosphate released from the fungus will be tested. In addition, the mutant MtPT4 lines will be used to explore fundamental questions about phosphate transport and the arbuscular mycorrhizal symbiosis, including the role of the different symbiotic interfaces and the importance of bi-directional nutrient exchange in a mutualistic symbiosis. Currently, the molecular events underlying arbuscule development are unknown. Comparative transcriptional profiling of the MtPT4 mutant lines and a M. truncatula arbuscule development mutant, will provide insights into the transcriptional events associated with structural and functional components of arbuscule development and phosphate transport in the symbiosis. Because phosphate limits plant production, an understanding of the AM/legume symbiosis has significant agricultural and ecological implications. Other Broader Impacts include the training of graduate students and postdoctoral fellows, as well as undergraduates and high school students.

在自然生态系统中，大多数维管开花植物与丛枝菌根（AM）真菌共生。这些互利的关联在根系中发展，真菌在其中定殖根细胞以从植物中获得碳，同时帮助植物从土壤中获得矿物质营养，特别是磷。 丛枝菌根共生体是几乎所有维管开花植物形成的共生体，在生态系统的生物多样性和功能中发挥着重要作用。其潜在机制尚不清楚，但AM真菌对植物磷营养的贡献以及对植物健康的影响显然是一个主要的促成因素。本计画的总体目标是剖析丛枝菌根共生中植物从真菌获得磷酸盐的机制。一个模式豆科植物，苜蓿，将用于这些分析。 丛枝菌根共生是一种高度共同进化的伙伴关系，其中两种共生体的分化导致专门的共生界面，使碳和磷的交换。在根细胞内，真菌形成高度分枝的菌丝，称为丛枝，它们被包裹在一种专门的植物膜中，称为丛枝周膜。先前的研究导致了一个独特的磷酸盐转运蛋白（MtPT 4）的鉴定，从蒺藜苜蓿，是专门位于周围的丛枝膜。目前的目标是评估涉及靶向MtPT 4的动脉周围膜的图案，并确定MtPT 4在磷酸盐转运中的共生作用。使用其中MtPT 4表达被破坏的转基因系，或通过TILLING获得的MtPT 4的功能丧失等位基因，将测试MtPT 4对于获得从真菌释放的磷酸盐是必需的假设。此外，突变MtPT 4线将用于探索磷酸盐运输和丛枝菌根共生的基本问题，包括不同的共生界面的作用和双向营养交换的重要性，在互利共生。 目前，有关丛枝发育的分子机制尚不清楚。MtPT 4突变株系和M. truncatula arbuscule发展突变体，将提供深入了解与结构和功能成分的丛枝发展和共生中的磷酸盐运输的转录事件。由于磷酸盐限制植物产量，因此了解AM/豆类共生关系具有重要的农业和生态意义。其他更广泛的影响包括培训研究生和博士后研究员，以及本科生和高中生。