Dissertation Research: Chloroplast Evolution of the Nonphotosynthetic Liverwort Cryptothallus Mirabilis (Aneuraceae)

论文研究：非光合地钱Cryptothallus Mirabilis（Aneuraceae）的叶绿体进化

• 批准号: 0408043
• 负责人: Bernard Goffinet
• 金额: $ 1.15万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0408043&HistoricalAwards=false
• 关键词: Dissertation; Research; Chloroplast; Evolution; Nonphotosynthetic

AbstractWithin bryophytes (mosses, liverworts, and hornworts), fungal associations are common only in hornworts and liverworts; however, only among liverworts is there a species that relies entirely on its fungal associate, rather than on photosynthesis, for fixed carbon. This dependence on an alternative carbon source is present only in one genus (two species) of liverworts: Cryptothallus (Aneuraceae). Cryptothallus mirabilis is non-photosynthetic, lacks the green pigment chlorophyll, and is therefore whitish yellow in appearance. Carbon is taken up from the fungus, which penetrates the intercellular spaces of the liverwort. The fungus, Tulasnella, satisfies its carbon demand through and ectomycorrhizal association with pine or birch trees. Among flowering plants, the evolution of a non-photosynthetic life strategy is accompanied by a reduction in the chloroplast genome. This reduction results in the loss (physically, or loss of function) of genes that code for enzymes involved in the reactions of photosynthesis. This award will support the dissertation research of a graduate student of Dr. Bernard Goffinet, Norman Wickett, investigating whether the patterns of gene loss observed in non-photosynthetic angiosperms are also present in non-flowering land plants, particularly bryophytes. To accomplish this, the complete chloroplast genome of C. mirabilis will be sequenced, as well as that of a closely related photosynthetic relative. Phylogenetic reconstruction will be used to identify the most closely related photosynthetic liverwort and to test hypotheses of genomic evolution. Comparisons can then be made between the two chloroplast genomes in order to identify changes associated with the loss of photosynthesis and to test hypotheses of genomic evolution. Chloroplast genome sequences will be obtained using a modified shotgun sequencing method developed for non-photosynthetic flowering plants.This study integrates genomics and phylogenetics in order to assess patterns of chloroplast genome evolution in a non-photosynthetic bryophyte. Much of the current understanding in this area arises from studies of flowering plants; this study, therefore, will significantly broaden the taxonomic diversity of studies addressing chloroplast genome evolution accompanying the loss of one of the most fundamental processes of life: photosynthesis. The results of this study will be made available to the public and the scientific community. In the latter case, the results will be particularly informative to current studies addressing the evolution of land plants in general. The unique natural history of this study, and the fundamental nature of its focal questions (genomic evolution when major selection forces are lost), should facilitate the dissemination of findings through local outreach activities and publications in popular journals.

AbstractWithin苔藓植物（苔藓，利弗沃特和霍恩沃尔特），真菌关联仅在霍恩沃尔特和利弗沃特中很常见。但是，只有在利弗沃特人中，有一个完全依赖其真菌助理而不是光合作用的物种用于固定碳。这种对替代碳源的依赖性仅存在于一个植物（两种）中：cryptothallus（Aneuraceae）。 密码丘比利氏菌是非光子合成的，缺乏绿色颜料叶绿素，因此外观是白色的。碳是从真菌中取出的，该真菌穿透了肝脏的细胞间空间。真菌Tulasnella通过与松树或桦树的外生相关性满足其碳需求。在开花植物中，非光合合成寿命策略的演变伴随着叶绿体基因组的降低。这种减少导致基因的损失（物理或功能丧失），这些基因为参与光合作用反应的酶编码。该奖项将支持Bernard Goffinet博士诺曼·韦特特（Norman Wickett）的研究生的论文研究，调查了非植物生物合成被子植物中观察到的基因损失模式是否也存在于非花水土地植物中，尤其是苔藓植物。为此，将对奇异梭状芽孢杆菌的完整叶绿体基因组进行测序，以及密切相关的光合作用相关的叶绿体基因组。系统发育重建将用于识别最密切相关的光合作用肝脏的肝脏并检验基因组进化的假设。然后可以在两个叶绿体基因组之间进行比较，以识别与光合作用丧失相关的变化并检验基因组进化的假设。叶绿体基因组序列将使用针对非光合合成开花植物开发的改良shot弹枪测序方法获得。这项研究整合了基因组学和系统发育学，以评估非脂质合成性乳藻中叶绿体基因组进化的模式。目前在这一领域的大部分理解都是由对开花植物的研究产生的。因此，这项研究将显着扩大针对叶绿体基因组进化的研究的分类多样性，伴随着最基本的生命过程之一的丧失：光合作用。这项研究的结果将提供给公众和科学界。在后一种情况下，结果将对目前的研究特别有用。这项研究的独特自然史以及其焦点问题的基本性质（丢失主要选择力量时的基因组进化），应该通过当地的外展活动和流行期刊的出版物来促进发现的传播。