Mobile introns and homing endonuclease genes in the mitochondrial genomes of fungi.

蓝斑真菌，如蛇瘤菌、格罗斯曼菌和角鼻虫，是由昆虫传播的媒介，它们使木材变色，从而降低木材的经济价值，因此引起经济关注。这些真菌也被称为类蛇口真菌，这类真菌包括树木病原体，如荷兰榆树病或橡树枯萎病的病原体。本研究计划部分集中于蓝斑真菌的分类和进化。表征蓝染真菌的线粒体基因组是本提案长期目标的一部分。这些真菌是专性需氧生物，因此功能线粒体对于这些生物在自然环境中具有竞争力至关重要。更直接的目标是了解真菌线粒体基因组（mtDNA）中移动遗传元件的起源和持久性，并检查这些元件对mtDNA稳定性和这些树状病原体潜在毒力的影响。本研究将重点研究长尾蛇及其相关物种（如O. novoo -ulmi、O. himal-ulmi和与长尾蛇相关的物种）的线粒体基因组特征。下一代测序的相对低成本和速度允许从各种代表的类蛇口真菌中测序约100个mtdna，结果数据的比较分析应该为鉴定这些经济上重要的真菌的种间标记提供可能的资源。此外，比较近亲物种的mtDNA也可以揭示I族和II族内含子等可移动元件对mtDNA基因组进化的影响。此外，这些可移动元件有时编码DNA切割酶，即归巢内切酶。这些酶在基因组学和生物技术中都有应用。归巢内切酶目前被用于基因组编辑应用，包括基因替换、突变和基因治疗。该研究将寻找和生物化学分析归巢内切酶，并试图解决它们的天然DNA靶点及其相互关系和其他mtDNA移动元件。最后，本课程将更详细地研究含有内含子的归巢内切酶基因。长期目标是开发一种调节开关，允许通过操纵内含子剪接在体内调节归巢内切酶的表达。有人提出，体内控制归巢内切酶活性将允许更精确的基因失活或修饰的时间。

Blue-stain fungi such as species of Ophiostoma, Grosmannia and Ceratocystis are vectored by insects and are of economic concerns as they discolour lumber, thus reducing the economic value of the wood. These fungi are also referred to as ophiostomatoid fungi and this group includes tree pathogens such as the causative agents of Dutch Elm Disease or Oak wilt. This research program in part focuses on the taxonomy and evolution of blue-stain fungi. Characterizing mitochondrial genomes of blue-stain fungi is part of the long term objectives of this proposal. These fungi are obligate aerobes thus functional mitochondrial are of upmost importance to these organisms in order to be competitive in their natural surroundings. The more immediate goals are to understand the origin and persistence of mobile genetic elements within fungal mitochondrial genomes (mtDNA) and to examine the implications these elements have on mtDNA stability and potentially on the virulence of these tree pathogens. This proposal will focus on characterizing the mitochondrial genomes of Ophiostoma ulmi and related species such as O. novo-ulmi, O. himal-ulmi and species related to the Ophiostoma piceae complex. The relative low cost and speed of next generation sequencing allows for sequencing of about 100 mtDNAs from various representatives of the ophiostomatoid fungi, comparative analysis of the resulting data should provide a resource for possible identifying inter-specific markers for identification of these economically important fungi. Also comparing the mtDNA of closely related species should reveal the impact of mobile elements such as group I and group II introns on mtDNA genome evolution. In addition these mobile elements sometimes encode DNA cutting enzymes, so called homing endonucleases. These enzymes have application in genomics and biotechnology. Homing endonucleases are currently employed in genome editing applications that involved gene replacement, mutagenesis and gene therapy. The proposed study will search for and biochemically analyze homing endonucleases and try to resolve their native DNA target sites and their relationships to each other and other mtDNA mobile elements. Finally this program will study in more detail a homing endonuclease gene that contains an intron. The long term goal is to develop a regulatory switch that permits in vivo regulation of homing endonuclease expression by manipulating intron splicing. It has been suggested that the in vivo control of homing endonuclease activity would allow for more precise timing of the inactivation or modification of genes.