Molecular analyses identify hybridization-mediated nuclear evolution in newly discovered fungal hybrids

Hybridization may be a major driver in the evolution of plant pathogens. In a high elevation Alpine larch stand in Montana, a novel hybrid fungal pathogen of trees originating from the mating of Heterobasidion irregulare with H. occidentale has been recently discovered. In this study, sequence analyses of one mitochondrial and four nuclear loci from 11 Heterobasidion genotypes collected in the same Alpine larch stand indicated that hybridization has increased allelic diversity by generating novel polymorphisms unreported in either parental species. Sequence data and ploidy analysis through flow cytometry confirmed that heterokaryotic (n+n) genotypes were not first generation hybrids, but were the result of multiple backcrosses, indicating hybrids are fertile. Additionally, all admixed genotypes possessed the H. occidentale mitochondrion, indicating that the hybrid progeny may have been backcrossing mostly with H. occidentale. Based on reticulate phylogenetic network analysis by PhyloN...

杂交作用可能是植物病原物演化的核心驱动力之一。近期，研究人员在蒙大拿州一处高海拔阿尔卑斯落叶松林分中，发现了一种由异担子菌（Heterobasidion irregulare）与西方异担子菌（Heterobasidion occidentale）交配产生的新型树木病原真菌杂交种。本研究对采自该林分的11个异担子菌基因型开展分析，对1个线粒体基因座与4个核基因座进行测序后发现，杂交作用通过产生双亲物种均未报道过的新型多态性，提升了等位基因多样性。测序数据与流式细胞术（Flow Cytometry）倍性分析结果证实，异核体（n+n）基因型并非第一代杂交种，而是经多次回交演化而来，这表明该杂交菌株具备育性。此外，所有混合基因型菌株均携带西方异担子菌的线粒体基因组，提示杂交子代主要与西方异担子菌发生回交。基于PhyloN开展的网状系统发育网络分析……