Phylogenetics and Plastid Genome Evolution of Vanilloideae (Orchidaceae)

香兰科（兰科）的系统发育和质体基因组进化

• 批准号: 0108100
• 负责人: Kenneth Cameron
• 金额: $ 13.14万
• 依托单位: New York Botanical Garden
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0108100&HistoricalAwards=false
• 关键词: Phylogenetics; Plastid; Genome; Evolution; Vanilloideae

A grant has been awarded to Dr. Kenneth M. Cameron at The New York Botanical Garden to continue his laboratory and field studies on the evolution and classification of the orchid subfamily Vanilloideae, which includes Vanilla planifolia -- the only orchid species out of approximately 25,000 that has significant agricultural value. These are considered an ancient lineage of relatively primitive orchids that are found worldwide in distribution. They have always been considered critical to fully understanding the evolution and classification of the large orchid family, but have resisted attempts to shoehorn them into traditional subfamilies. Previous molecular research by Dr. Cameron has shown these vanilloid orchids to represent a separate, distinct subfamily that is the most primitive of all but two genera of orchids. However, the relationships of the species within the subfamily are still unclear. These findings emphasize the evolutionarily pivotal position occupied by these plants and the need for further, in-depth systematic investigation. Specifically, the research will include a molecular component that will focus on constructing a solid evolutionary tree for the subfamily using DNA sequences from a suite of nuclear, chloroplast, and mitochondrial genes. However, the molecular aspect of the project will not be limited to DNA sequencing. In addition, select genes and their products from within the chloroplast genome will be studied in detail to better understand the pattern and process of degeneration of the photosynthetic apparatus among the non-green taxa that live as parasites on soil fungi. Already, Dr. Cameron has investigated three different classes of photosynthesis genes, and has discovered that two of the three (rbcL and psaB, but not atpB) are characterized by significant deletions in some of the non-photosynthetic taxa, and extremely high rates of mutation in others. These findings suggest that the vanilloid orchids are in the early stages of chloroplast genome degradation. They are, therefore, an ideal group of organisms in which to study this biological phenomenon. Finally, in addition to molecular research, new studies on floral morphology and pollination biology in the group will be initiated. Many of the vanilloid taxa are characterized by complex flowers with prominent petal ornamentation in the form of mobile scales and bristles. These structures, in particular, are unlike any other in the orchid family. They deserve careful examination in order to understand their form, function, and evolutionary derivation. The vanilloid orchids have been long recognized as an economically valuable and unique group of plants, but several aspects of their natural history have been the source of controversy among biologists. A more thorough knowledge of this pivotal group undoubtedly will be valuable to our understanding of the evolution and diversity within the second largest family of flowering plants on Earth. Despite the economic importance of Vanilla to humankind, there exist few thorough systematic investigations of these plants. Comparative morphological, anatomical, and pollination studies of the group are also lacking. For these reasons, the combined results of these morphological and molecular studies should provide a solid phylogeny of Vanilloideae for which nomenclatural issues, patterns of biogeography, trends in floral morphology, and genome evolution can be examined. Few of the vanilloid orchid species take to cultivation. As a consequence, many are endangered or already extinct. It is imperative and warranted, therefore, that systematic research continues on this fascinating and pivotal group of orchids if their unique interactions with fungi and animal pollinators are to be understood before they are lost to habit destruction and overcollecting.

已向纽约植物园的肯尼斯·M·卡梅伦（Kenneth M. Cameron）博士授予了一笔赠款，以继续他的实验室和现场研究，以了解兰花亚家族香草果的进化和分类，其中包括香草planifolia，这是唯一的兰花物种，这是大约25,000种具有巨大农业价值的兰花。 这些被认为是一个古老的血统，这些谱系是相对原始的兰花，它们在全球分布中被发现。 它们一直被认为是充分理解大型兰花家族的进化和分类至关重要的，但是拒绝将它们剥离成传统的亚家族的尝试。 卡梅伦博士先前的分子研究表明，这些香草兰花代表了一个独立的，独特的亚家族，这是两个兰花属最原始的。 但是，该物种在亚科中的关系仍不清楚。 这些发现强调了这些植物所占据的进化关键位置，以及需要进一步，深入的系统研究。具体而言，该研究将包括一个分子成分，该分子成分将着重于使用来自核，叶绿体和线粒体基因的DNA序列为亚家族构建固体进化树。 但是，该项目的分子方面不仅限于DNA测序。 此外，将详细研究从叶绿体基因组中进行的精选基因及其产物，以更好地了解非绿色分类群中光合作用的模式和变性的模式和过程，这些分类群生存为土壤真菌上的寄生虫。 卡梅伦博士已经研究了三种不同类别的光合作用基因，并发现三个（RBCL和PSAB，但不是ATPB）中的两个的特征是在某些非斑点合成类群中的显着缺失，而其他突变率极高。 这些发现表明，香草兰花处于叶绿体基因组降解的早期阶段。 因此，它们是研究这种生物学现象的理想群体。 最后，除了分子研究外，还将启动有关该组花卉形态和授粉生物学的新研究。 许多香草群的特征是复杂的花朵，具有突出的花瓣装饰，形式是移动尺度和刷毛的形式。 这些结构尤其与兰花家族中的其他结构不同。 他们应该仔细检查以了解其形式，功能和进化推导。 长期以来，香草兰花被认为是经济上有价值且独特的植物群体，但其自然历史的几个方面一直是生物学家中争议的根源。 毫无疑问，对这个关键群体的更透彻的了解对于我们对地球上第二大开花植物家族中的演变和多样性的理解将是有价值的。 尽管香草对人类具有经济上的重要性，但对这些植物的系统调查很少。 该小组的比较形态学，解剖学和授粉研究也缺乏。 由于这些原因，这些形态学和分子研究的综合结果应提供固体系统发育，对命名自然问题，生物地理学模式，花卉形态的趋势和基因组演化的趋势。 几乎没有香草兰花物种耕种。 结果，许多人是濒危或已经灭绝的。 因此，如果兰花与真菌和动物传粉媒介的独特互动在失去习惯破坏和过度挑战之前，应理解它们与真菌和动物传粉媒介的独特相互作用，则必须在这种引人入胜且关键的兰花群体上进行系统的研究继续进行系统的研究。