Collaborative Research: Comparative analysis of fern LEAFY genes and their regulatory network

花代表了进化创新的一个经典例子，它使开花植物成为陆地植物中最成功、物种最丰富的一类。因此，深入了解开花背后的基因是植物进化生物学的一个重要课题。虽然没有花的植物有明显与花发育基因同源的基因，但它们的功能大多是未知的。该研究小组将调查一种非开花植物——新兴的模式蕨类角蕨（Ceratopteris richardii）——中花朵发育基因的祖先作用。该项目将促进：1)与国家和地方项目合作，增加代表性不足的少数民族在科学领域的代表性（例如，通过参加国家实验室日和加州大学戴维斯分校生物学本科学者计划）；2)科研与教学相结合：如加州大学戴维斯分校青年学者计划，为加州高中生提供暑期研究机会，为没有计算经验的学生开设本科生物信息学实验课；3)将李氏弧菌实验纳入教学实验室，并将其纳入伯克自然历史博物馆年度女生科学项目（华盛顿大学6 -8年级）的植物进化实践研讨会；(4)培养下一代科学家。人们对转录因子和发育程序是如何被进化创新所选择的，以及基因复制在这一过程中扮演什么角色越来越感兴趣。在被子植物中，叶状植物（LEAFY， LFY）编码一个诱导花形成的转录调控因子；它也存在于苔藓中，在那里它控制着合子的早期细胞分裂，在蕨类植物中，它促进配子体和孢子体世代的细胞分裂。LFY在陆地植物中的保存表明，它在花发育之外一定具有重要的祖先功能，最近在蕨类植物中的发现支持了这一假设。蕨类植物C. richardii是维管植物谱系的代表，位于苔藓和开花植物之间的进化树上。本项目的目的是研究蕨类植物的两个绿叶基因是如何分配顶端细胞活性的，并确定每个基因实现其细胞增殖功能的基因网络。具体的研究问题是：1)每个LFY同源基因CrLFY1和CrLFY2在角蕨中的作用是什么？这将通过位点特异性基因表达和原位杂交、功能丧失和功能获得以及每个基因的pcrlfy报告基因转基因来解决；2) CrLFY1和CrLFY2的直接和下游靶点是什么？这将通过ChIP-Seq和诱导型LFY构建体来确定蕨类LFY基因的靶点。鉴于LFY在被子植物发育及其保护中的节点作用，该研究应该为其他主要调控因子的进化研究提供关键范例。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Flowers represent a classic example of evolutionary innovation, one that made the flowering plants the most successful and species rich group of land plants. Hence, a deep understanding of the genes underlying flowering is an important topic in plant evolutionary biology. While plants that do not have flowers have genes that are clearly homologous to flower development genes, their function is mostly unknown. The research team will investigate the ancestral role of a flower development gene in a non-flowering plant, the emerging model fern Ceratopteris richardii. This project will facilitate: 1) Working with national and local programs to increase the representation of under-represented minorities in the sciences (by participating e.g., in National Lab Day and UC Davis Biology Undergraduate Scholars Program); 2) Integrating research and teaching activities: e.g., UC Davis Young Scholars Program that provides summer research opportunities for California high school students, and development of undergraduate bioinformatics lab class for students without previous computational experience; 3) Incorporating experiments with C. richardii into teaching labs and into a hands-on workshop on plant evolution for the annual Burke Museum of Natural History Girls in Science program (UW, 6th-8th graders); 4) Training of the next generation of scientists.There is growing interest in understanding how transcription factors and developmental programs are co-opted for evolutionary innovation, and what role gene duplications play in this process. LEAFY (LFY) encodes a transcriptional regulator that induces flower formation in angiosperms; it is also present in mosses, where it governs early cell divisions of the zygote, and in ferns where it promotes cell division in both the gametophyte and the sporophyte generations. The conservation of LFY across land plants suggests that it must have important ancestral function(s) outside of flower development, a hypothesis supported by recent findings in fern. The fern C. richardii is a representative of a lineage of vascular plants that lies midway in the evolutionary tree between mosses and flowering plants. The goal of this project is to investigate how apical cell activity is partitioned among the two fern LEAFY genes and determine the gene network that each uses to achieve its cell proliferation functions. The specific research questions are: 1) What is the function of each LFY homolog CrLFY1 and CrLFY2 in the fern Ceratopteris richardii? This will be addressed via locus-specific gene expression and in situ hybridization, loss- and gain-of-function and pCrLFY-reporter transgenics for each gene; 2) What are the direct and downstream targets of CrLFY1 and CrLFY2? This will be addressed using ChIP-Seq and inducible LFY constructs to define targets of fern LFY genes. Given the nodal role of LFY in angiosperm development and its conservation throughout land plants, this research should serve as a key example for evolutionary studies of other master regulators.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.