Collaborative Research: Transitions and Transcriptomics: a Novel Approach to Understanding Shifts in Floral Developmental Pathways Preceding the Origin of the Pentapetalae

开花植物是地球上最丰富和多样化的植物生命形式。这种优势在很大程度上是由于五瓣亚科的进化成功，其特征是以五成倍数的轮生花部分为特征，占所描述物种的70%以上。相反，在数量较少的开花植物群体中，花的部分以三的倍数(例如，单子叶)、两个或可变数量排列。向五瓣轮生的转变发生在大约1亿年前，这似乎是最成功的进化创新之一，不仅是开花植物，而且是整个绿色植物。这项研究将调查促成这一古老进化事件的潜在基因变化的进化。它有望发现产生典型五瓣花的新的和/或修改的遗传途径，这是植物进化的主要谜团之一。几名本科生将接受系统发育和分子生物学方法和分析方面的培训，高中教师将通过暑期研讨会参与研究。生成的数据将在网上免费分享，并将为其他研究人员和公众提供工具，以调查有关开花植物进化的其他问题。研究人员将在一个具有系统发育代表性的开花植物样本中对花发育过程中表达的基因进行测序，并使用最先进的转录组分析技术来实现三个主要目标。首先，将重建五瓣亚科分支所属谱系之间的系统发育关系。在转移到五角形轮花之前的谱系的牢固解决的系统发育关系目前缺乏，但对于解释作为这一关键形态创新基础的遗传变化的进化序列是关键的。其次，将使用几种比较方法来识别、确定时间和确定早于五瓣亚科起源的全基因组和/或基因复制事件(S)的进化影响。全基因组复制事件发生在五瓣瓣之前是被广泛承认的，但它们的确切位置是不确定的。最后，RNA-seq和原位杂交方法将被用来推断非五瓣花和五瓣花的基因表达的空间模式，以确定与后者向轮生五花体转变相关的基因表达变化。这些方法的结合将为我们对开花植物进化的理解提供令人兴奋的新见解。

Flowering plants are the most abundant and diverse form of plant life on Earth. This dominance is largely due to the evolutionary success of one group, the Pentapetalae, characterized by whorled flower parts in multiples of five, which account for over 70% of described species. In contrast, flower parts are arranged in multiples of three (monocots, for example), two, or a variable number in less abundant groups of flowering plants. The shift to whorled pentamery of the Pentapetalae occurred about 100 million years ago, and appears to have been one of the most successful evolutionary innovations of not only flowering plants, but of green plants in general. This research will investigate the evolution of the underlying genetic changes that contributed to this ancient evolutionary event. It promises to discover the new and/or modified genetic pathways that produced the typical Pentapetalae flower, one of the major mysteries of plant evolution. Several undergraduates will be trained in phylogenetic and molecular biology methods and analyses, and high school teachers will participate in the research through a summer workshop. Data generated will be shared freely online and will provide tools for other researchers and the public to investigate other questions about flowering plant evolution. The researchers will sequence genes expressed during flower development in a phylogenetically representative sample of flowering plants and employ state-of-the-art transcriptome analysis techniques to achieve three major goals. Firstly, phylogenetic relationships among lineages subtending the Pentapetalae clade will be reconstructed. Robustly resolved phylogenetic relationships of the lineages preceding the shift to the pentamerous whorled flower are currently lacking but pivotal to interpreting the evolutionary sequence of genetic changes that underlie this key morphological innovation. Secondly, several comparative methods will be used to identify, date, and determine the evolutionary impact of whole-genome and/or gene duplication event(s) that predate the origin of the Pentapetalae. The occurrence of whole-genome duplication events prior to Pentapetalae is widely acknowledged but their precise positions are uncertain. Lastly, RNA-seq and in situ hybridization approaches will be used to infer spatial patterns of gene expression in non-Pentapetalae versus Pentapetalae flowers to identify gene expression changes that correlate with a shift to whorled pentamery in the latter. Together, this integration of approaches will provide exciting new insights into our understanding of flowering plant evolution