Collaborative Research: EDGE CMT: Genomic and molecular bases of pollination syndrome evolution in monkeyflowers

复杂性状（如人类身高）的变异通常是由多个基因引起的。鉴定和表征这些多基因性状的致病基因和突变仍然是生物学的核心挑战。植物多基因适应的一个最有趣的例子是授粉综合征，这是一套花的特征，使花和它们的动物传粉者（如蜜蜂、蜂鸟、飞蛾）之间有专门的联系。例如，蜂鸟传粉的花通常体积大，颜色红色，花蜜丰富，生殖器官发达，而蜜蜂传粉的花通常颜色多样（但不是红色），花蜜较少，插入生殖器官，有清晰的落地平台。从一种传粉综合征到另一种传粉综合征的进化转变需要多种花性状的协调变化，每种性状由多个基因控制，然而这些开关在自然界中许多植物类群中发生得很快。本研究采用一种新的遗传模型系统——猴花，来研究授粉综合征在基因组和分子水平上的开关是如何发生的。此外，本研究透过传粉症候群的视角，将研究与学生教育及公众推广相结合。具体活动包括在康涅狄格大学校园的一个普通花园组织传粉者观察实验，以提高公众对动物授粉服务的认识，在哈弗福德学院创建一个基于生物信息学课程的本科生研究体验，以及制作专业视频，将授粉综合征研究带到了生活中，并将在一个订阅量很高的YouTube频道Science IRL（“现实生活”）上发布。本项目的总体目标是系统剖析三种密切相关的猴花（Mimulus）物种的花性状变异的基因组和分子基础，这些物种表现出三种不同的授粉综合征，包括蜜蜂授粉的M. lewisii，蜂鸟授粉的M. cardinalis和自花授粉的M. parishii。这些物种可以通过稳定的转基因进行精细的基因定位和严格的功能询问。我们计划通过追求以下具体目标来实现我们的总体目标：(i)产生高质量的近等基因系（NILs），这些系与亲本物种只有一个来自其他物种的花性状基因座的差异，并利用NILs对授粉综合征开关背后的每个数量性状基因座（QTL）进行遗传剖析。（ii）利用稳定的转基因实验对单个qtl下的致病基因和突变进行功能表征。（iii）利用加权基因共表达网络分析构建控制授粉综合征组成性状的基因调控网络/模块。这项研究的结果有望为传粉综合征开关背后的因果基因提供深入的全基因组视角，确定一组控制个体花性状的基因调控模块，这些模块应该广泛适用于其他植物系统，并揭示新的分子机制，为植物和其他生物的表型进化研究提供信息。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。

Variation of complex traits (e.g., human height) are usually caused by multiple genes. Identification and characterization of the causal genes and mutations underlying these polygenic traits remain a central challenge in biology. One of the most intriguing examples of polygenic adaptations in plants is the pollination syndrome, a suite of floral traits that enable specialized associations between flowers and their animal pollinators (e.g., bees, hummingbirds, hawkmoths). For example, hummingbird-pollinated flowers are usually large in size, red in color, with copious nectar production and exerted reproductive organs, whereas bee-pollinated flowers usually display various colors (but not red), a smaller quantity of nectar, inserted reproductive organs, and a clear landing platform. Evolutionary transitions from one pollination syndrome to another require coordinated changes of multiple floral traits, with each trait controlled by multiple genes, yet these switches occur rapidly in nature in many plant groups. This study employs a new genetic model system, monkeyflowers, to investigate how pollination syndrome switches occur at the genomic and molecular level. Furthermore, this study integrates research with student education and public outreach through the lens of pollination syndromes. Specific activities include organized pollinator observation experiments in a common garden on the University of Connecticut campus to raise public awareness of animal pollination service, creation of a bioinformatic Course-based Undergraduate Research Experience at Haverford College, and production of professional videos that bring pollination syndrome research to life and that will be released on a highly subscribed YouTube channel, Science IRL (‘in real life’).The overall objective of this project is to systematically dissect the genomic and molecular bases of floral trait variation among three closely related monkeyflower (Mimulus) species that display three distinct pollination syndromes, including the bee-pollinated M. lewisii, the hummingbird-pollinated M. cardinalis, and the self-pollinated M. parishii. These species are amenable to fine-scale genetic mapping and rigorous functional interrogation through stable transgenics. We plan to accomplish our overall objective by pursuing the following specific aims: (i) Generate high-quality near-isogenic lines (NILs), which differ from a parental species by only a single floral trait locus introgressed from another species, and use the NILs to genetically dissect each quantitative trait locus (QTL) underlying the pollination syndrome switches. (ii) Functionally characterize the causal genes and mutations under individual QTLs using stable transgenic experiments. (iii) Construct gene regulatory networks/modules that control pollination syndrome component traits using weighted gene co-expression network analysis. Results from this study are anticipated to provide an in-depth, genome-wide view of the causal genes underlying pollination syndrome switches, to identify a set of gene regulatory modules controlling individual floral traits that should be widely applicable in other plant systems, and to reveal novel molecular mechanisms that can inform studies of phenotypic evolution in not only plants, but also other organisms.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.