Departments of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa.
CSIR-Food Research Institute, Microbiology and Mushroom Research Division, P. O. Box, M20, Accra, Ghana.
G3 (Bethesda). 2023 Dec 6;13(12). doi: 10.1093/g3journal/jkad205.
Siderophores are important for ferric iron solubilization, sequestration, transportation, and storage, especially under iron-limiting conditions such as aerobic conditions at high pH. Siderophores are mainly produced by non-ribosomal peptide synthetase-dependent siderophore pathway, non-ribosomal peptide synthetase-independent siderophore synthetase pathway, or the hybrid non-ribosomal peptide synthetases/non-ribosomal peptide synthetases-independent siderophore pathway. Outcompeting or inhibition of plant pathogens, alteration of host defense mechanisms, and alteration of plant-fungal interactions have been associated with fungal siderophores. To understand these mechanisms in fungi, studies have been conducted on siderophore biosynthesis by ascomycetes with limited focus on the basidiomycetes. Armillaria includes several species that are pathogens of woody plants and trees important to agriculture, horticulture, and forestry. The aim of this study was to investigate the presence of non-ribosomal peptide synthetases-independent siderophore synthetase gene cluster(s) in genomes of Armillaria species using a comparative genomics approach. Iron-dependent growth and siderophore biosynthesis in strains of selected Armillaria spp. were also evaluated in vitro. Two distinct non-ribosomal peptide synthetases-independent siderophore synthetase gene clusters were identified in all the genomes. All non-ribosomal peptide synthetases-independent siderophore synthetase genes identified putatively encode Type A' non-ribosomal peptide synthetases-independent siderophore synthetases, most of which have IucA_IucC and FhuF-like transporter domains at their N- and C-terminals, respectively. The effect of iron on culture growth varied among the strains studied. Bioassays using the CAS assay on selected Armillaria spp. revealed in vitro siderophore biosynthesis by all strains irrespective of added FeCl3 concentration. This study highlights some of the tools that Armillaria species allocate to iron homeostasis. The information generated from this study may in future aid in developing molecular based methods to control these phytopathogens.
铁载体对于铁的溶解、螯合、运输和储存非常重要，尤其是在铁限制条件下，如高 pH 值下的需氧条件。铁载体主要通过非核糖体肽合成酶依赖性铁载体途径、非核糖体肽合成酶非依赖性铁载体合成酶途径或混合非核糖体肽合成酶/非核糖体肽合成酶非依赖性铁载体途径产生。真菌铁载体与竞争或抑制植物病原体、改变宿主防御机制以及改变植物-真菌相互作用有关。为了在真菌中理解这些机制，人们已经对子囊菌中的铁载体生物合成进行了研究，而对子囊菌的研究则相对较少。蜜环菌属包括几种木质植物和树木的病原体，这些植物和树木对农业、园艺和林业很重要。本研究旨在利用比较基因组学方法研究蜜环菌属物种基因组中是否存在非核糖体肽合成酶非依赖性铁载体合成酶基因簇，并评估所选蜜环菌属菌株的铁依赖性生长和铁载体生物合成。在所有基因组中都鉴定出了两个截然不同的非核糖体肽合成酶非依赖性铁载体合成酶基因簇。鉴定出的所有非核糖体肽合成酶非依赖性铁载体合成酶基因都推测编码 A'型非核糖体肽合成酶非依赖性铁载体合成酶，其中大多数在其 N 和 C 末端分别具有 IucA_IucC 和 FhuF 样转运体结构域。研究中，菌株的铁对培养生长的影响各不相同。使用 CAS 测定法对选定的蜜环菌属菌株进行的生物测定显示，所有菌株均在体外合成铁载体，而与添加的 FeCl3 浓度无关。本研究强调了蜜环菌属物种分配给铁稳态的一些工具。本研究产生的信息将来可能有助于开发基于分子的方法来控制这些植物病原体。
