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Kenneth M.博士颁发了一笔赠款。卡梅隆在纽约植物园继续他的实验室和实地研究的进化和分类的兰花亚科香草，其中包括香草planifolia -唯一的兰花物种约25,000具有重要的农业价值。 这些被认为是一个古老的血统相对原始的兰花是发现世界各地的分布。 它们一直被认为是充分理解大型兰花家族的进化和分类的关键，但一直抵制将它们硬塞进传统亚科的尝试。 卡梅隆博士先前的分子研究表明，这些香草类兰花代表了一个独立的，独特的亚科，是最原始的所有，但两个属的兰花。 然而，该亚科内的物种关系仍不清楚。 这些发现强调了这些植物在进化上所占据的关键地位，以及进一步深入系统研究的必要性。具体来说，该研究将包括一个分子组成部分，重点是使用来自一套核，叶绿体和线粒体基因的DNA序列为该亚科构建一个坚实的进化树。 然而，该项目的分子方面将不仅限于DNA测序。 此外，将详细研究叶绿体基因组中的选择基因及其产物，以更好地了解作为土壤真菌寄生虫生活的非绿色类群中光合机构退化的模式和过程。 卡梅隆博士已经研究了三种不同类型的光合作用基因，并发现其中两种（rbcL和psaB，而不是atpB）在某些非光合作用类群中具有显著的缺失，而在其他类群中具有极高的突变率。 这些结果表明，香草类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现象的理想生物群体。 最后，除了分子研究外，还将在该小组中启动花形态和授粉生物学的新研究。 许多香草类植物的特征是复杂的花，花瓣突出，呈移动的鳞片和刚毛的形式。 特别是这些结构，与兰科植物中的任何其他结构都不同。 它们值得仔细研究，以了解它们的形式，功能和进化起源。 香草兰长期以来被认为是一种具有经济价值和独特的植物，但其自然历史的几个方面一直是生物学家之间争议的来源。 对这一关键群体的更深入了解无疑将有助于我们了解地球上第二大开花植物家族的进化和多样性。 尽管香草对人类的经济重要性，但对这些植物的彻底系统调查很少。 比较形态学，解剖学和传粉的研究组也缺乏。 由于这些原因，这些形态学和分子生物学研究的综合结果应该提供一个坚实的Vanilloideae的命名问题，模式的植物地理学，花形态的趋势，和基因组进化可以检查。 很少有香草类兰花的品种可以种植。 因此，许多物种濒临灭绝或已经灭绝。 因此，如果要在兰花因习惯破坏和过度采集而消失之前了解它们与真菌和动物传粉者的独特相互作用，那么对这一迷人而关键的兰花群体进行系统的研究是必要的。