Department of Microbiology, University of Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria.
Institute of Molecular Biology/Biocenter, Medical University Innsbruck, Innrain 80-82, 6020, Innsbruck, Austria.
Biometals. 2020 Jun;33(2-3):137-146. doi: 10.1007/s10534-020-00238-0. Epub 2020 May 3.
More than 70% of vascular plant species live in symbiosis with arbuscular mycorrhizal (AM) fungi. In addition to other effects this symbiosis is known for its significance for plant nutrition including iron. Fungal iron mobilization from soil is commonly dependent on siderophores. This study reports on a search for such iron-chelators in root tissue of Tagetes patula nana var. plena colonized by Gigaspora margarita. The AM colonized plants and uninoculated controls were grown under strictly axenic conditions. HPLC analyses of aqueous extracts from plant roots have provided clear evidence for the presence of a rhizoferrin type siderophore, named glomuferrin, in root tissue of mycorrhizal seedlings. Results from HPLC analytical work are seconded by molecular biological data: A BLASTp search revealed that the AM fungal species Gigaspora rosea, Rhizophagus irregularis (formerly Glomus intraradices), Glomus cerebriformis and Diversispora epigea encode a non-ribosomal peptide synthetase (NRPS)-independent siderophore synthase (NIS), which is homologous to the rhizoferrin synthetase of Rhizopus delemar. Thus this study indicates that the biosynthesis of rhizoferrin type siderophores such as glomuferrin (= bis-imidorhizoferrin) may be widespread in the AM symbiosis.
超过 70%的维管植物物种与丛枝菌根（AM）真菌共生。除了其他影响外，这种共生关系还因其对植物营养的重要性而闻名，包括铁。真菌从土壤中释放铁通常依赖于铁载体。本研究报告了在被大丽花花冠球囊霉（Gigaspora margarita）定殖的 Tagetes patula nana var. plena 根组织中寻找这种铁螯合剂的研究。在严格无菌条件下种植 AM 定殖植物和未接种对照植物。对植物根系水提物的 HPLC 分析为根组织中存在一种称为 glomuferrin 的根铁载体（rhizoferrin 型铁载体）提供了明确证据。来自 HPLC 分析工作的结果得到了分子生物学数据的支持：BLASTp 搜索表明，AM 真菌物种大丽花花冠球囊霉（Gigaspora rosea）、不规则根内球囊霉（Rhizophagus irregularis，以前称为 Glomus intraradices）、聚丛球囊霉（Glomus cerebriformis）和表生 Diversispora（Diversispora epigea）编码一种非核糖体肽合成酶（NRPS）独立的铁载体合成酶（NIS），该酶与 Rhizopus delemar 的根铁载体合成酶同源。因此，本研究表明，rhizoferrin 型铁载体（如 glomuferrin = 双亚氨基根铁载体）的生物合成可能在 AM 共生中广泛存在。
