Shahi Shermineh, Beerens Bas, Bosch Martin, Linmans Jasper, Rep Martijn
Molecular Plant Pathology, University of Amsterdam, Amsterdam, The Netherlands.
Molecular Plant Pathology, University of Amsterdam, Amsterdam, The Netherlands.
Fungal Genet Biol. 2016 Jun;91:20-31. doi: 10.1016/j.fgb.2016.03.003. Epub 2016 Mar 21.
Recent studies have shown horizontal transfer of chromosomes to be a potential key contributor to genome plasticity in asexual fungal pathogens. However, the mechanisms behind horizontal chromosome transfer in eukaryotes are not well understood. Here we investigated the role of conidial anastomosis in heterokaryon formation between incompatible strains of Fusarium oxysporum and determined the importance of heterokaryons for horizontal chromosome transfer. Using live-cell imaging we demonstrate that conidial pairing of incompatible strains under carbon starvation can result in the formation of viable heterokaryotic hyphae in F. oxysporum. Nuclei of the parental lines presumably fuse at some stage as conidia with a single nucleus harboring both marker histones (GFP- and RFP-tagged) are produced. Upon colony formation, this hybrid offspring is subject to progressive and gradual genome rearrangement. The parental genomes appear to become spatially separated and RFP-tagged histones, deriving from one of the strains, Fol4287, are eventually lost. With a PCR-based method we showed that markers for most of the chromosomes of this strain are lost, indicating a lack of Fol4287 chromosomes. This leaves offspring with the genomic background of the other strain (Fo47), but in some cases together with one or two chromosomes from Fol4287, including the chromosome that confers pathogenicity towards tomato.
最近的研究表明，染色体水平转移是无性真菌病原体基因组可塑性的一个潜在关键因素。然而，真核生物中水平染色体转移背后的机制尚未得到充分理解。在这里，我们研究了分生孢子吻合在尖孢镰刀菌不亲和菌株之间异核体形成中的作用，并确定了异核体对水平染色体转移的重要性。通过活细胞成像，我们证明了在碳饥饿条件下不亲和菌株的分生孢子配对可导致尖孢镰刀菌中形成有活力的异核菌丝。亲本系的细胞核可能在某个阶段融合，因为产生了带有两种标记组蛋白（绿色荧光蛋白和红色荧光蛋白标记）的单核分生孢子。菌落形成后，这种杂交后代会经历渐进和逐渐的基因组重排。亲本基因组似乎在空间上分离，并且来自其中一个菌株Fol4287的红色荧光蛋白标记组蛋白最终丢失。通过基于聚合酶链反应的方法，我们表明该菌株大多数染色体的标记丢失，表明缺乏Fol4287染色体。这使得后代具有另一个菌株（Fo47）的基因组背景，但在某些情况下还带有来自Fol4287的一两条染色体，包括赋予对番茄致病性的染色体。
