Interplay of chelating and reducing root exudates in plant iron acquisition

植物铁获取过程中螯合和减少根系分泌物的相互作用

基本信息

批准号：
291474925
负责人：
Dr. Günther Weber
金额：
--
依托单位：
Institut für Bodenforschung (IBF)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/291474925?language=en
关键词：
Interplay chelating reducing root exudates

项目摘要

Due to the low iron (Fe) solubility in most soils, plants have evolved Fe acquisition strategies that are mainly based on the chelation and reduction of ferric Fe. While graminaceous plants release mugineic acid-type siderophores from their roots for ferric Fe chelation, non-graminaceous plants rely primarily on the reduction of ferric Fe which is compromised at high pH. Recently, a new class of coumarin-type siderophores has been identified in root exudates that mediate ferric Fe chelation, however, due to their high chemical versatility their mode of action in the rhizosphere is still unclear. Therefore, the present project aims at i) identifying new exudate compounds with novel or specific Fe-related functions, in particular regarding the chelation and/or reduction of Fe(III) and to characterize modifications and chemical interactions of these compounds on their way from the release by root cells through the root apoplast into the rhizosphere soil and back; ii) examining synergisms among individual root exudates involved in Fe mobilization by from Fe-bearing phases in the soil; iii) identifying and quantifying the contribution and interplay of chemical and biological processes involved in Fe acquisition via plant-exuded reductants and iron ligands in the rhizosphere. To address a set of 8 defined hypotheses, two German and two Austrian labs from molecular plant nutrition, analytical chemistry, rhizosphere ecology and biogeochemistry will collect root exudates from hydroponic and rhizosphere systems, conduct metal-chelate speciation by advanced mass spectrometry-coupled techniques, assess Fe chelation and redox chemistry of root exudates from wild-type and mutant plants and employ thermodynamic and kinetic modelling approaches. This proposal promises to chemically identify key players in root exudates and to describe their mode of action as chelators, reductants or redox shuttles for an improved Fe nutrition in plants.

由于大多数土壤中铁 (Fe) 的溶解度较低，植物已经进化出主要基于三价铁的螯合和还原的铁获取策略。虽然禾本科植物从其根部释放麦根酸型铁载体来螯合三价铁，但非禾本科植物主要依赖于三价铁的还原，而三价铁在高pH值下会受到损害。最近，在根分泌物中发现了一类新的香豆素型铁载体，可介导三价铁螯合，然而，由于其高度的化学多功能性，其在根际的作用方式仍不清楚。因此，本项目的目标是 i) 识别具有新的或特定的 Fe 相关功能的新渗出物化合物，特别是关于 Fe(III) 的螯合和/或还原，并表征这些化合物在从根细胞通过根质外体释放到根际土壤并返回； ii) 检查土壤中含铁相参与铁动员的各个根系分泌物之间的协同作用； iii) 识别和量化通过根际植物分泌的还原剂和铁配体获取铁所涉及的化学和生物过程的贡献和相互作用。为了解决一组 8 个明确的假设，来自分子植物营养、分析化学、根际生态学和生物地球化学的两个德国和两个奥地利实验室将从水培和根际系统中收集根系分泌物，通过先进的质谱耦合技术进行金属螯合物形态形成，评估野生型和突变植物根部分泌物的铁螯合和氧化还原化学，并采用热力学和动力学建模方法。该提案有望通过化学方法识别根系分泌物中的关键参与者，并描述其作为螯合剂、还原剂或氧化还原梭的作用方式，以改善植物中的铁营养。