RESEARCH-PGR: Comparative Genomics and Biochemistry of Colored Nectars

近90%的开花植物产生花蜜，花蜜的数量和组成与动物传粉的效率有关，动物传粉的效率影响了全球115种主要粮食作物中的87种(~76%)的产量。仅在美国，花蜜的年产值就达到290亿美元，占总粮食产量的三分之一。虽然糖是主要的花蜜溶质，但约10%的花蜜干重代表了许多类型的非糖溶质，包括特殊的代谢物，如色素。色素在整个生命树的生物相互作用中扮演着至关重要的角色，天然色素每年的全球市场价值为50亿美元。这个项目将使用比较基因组学跨学科的方法来测试中心假设，即彩色蜜汁含有新的和已知的色素，这种色素是通过具有与传粉者视觉相协调的光谱性质而选择性地受到青睐的。这项研究中概述的活动是全新的，将通过(1)系统地描述不同物种的花蜜色素；(2)确定蜜腺在多大程度上可以主动控制非糖花蜜含量，重点是花蜜色素；(3)了解进化和自然历史如何影响花蜜色素的质量；(4)鉴定和表征参与色素合成的酶；以及(5)系统地评估花蜜色素的真实生物学功能，从而为在基因组范围内实现基本的动植物互惠关系提供新的见解。就更广泛的影响而言，该项目将通过为本科生、研究生和中学生提供研究培训经验，帮助培训下一代植物生物学家。此外，该项目将利用公众对保护植物的广泛兴趣：传粉者通过公民科学项目相互作用。植物与传粉者的相互作用至少部分驱动了在被子植物中观察到的大量物种辐射，不仅导致花朵大小和形态的极端多样化，而且还伴随着引诱剂(颜色和气味)和奖励(花蜜和花粉)背后的化学成分。虽然罕见，但有一个已经多次进化的花卉特征是彩色花蜜，这被认为是对潜在传粉者的一种视觉奖励。已知大约有70种植物可以产生彩色蜜汁，但这些色素的特性、相关的合成和真正的生物功能尚未被描述。为了解决这一知识差距，该项目的首要目标是在系统发育和进化框架内破译花蜜色素的多样性、合成和功能。本项目的具体目标包括：1)通过LC-MS/MS对20多个不同谱系的类群中的蜜色素进行系统鉴定，包括具有不同颜色蜜汁的多个姊妹类群。2)蜜腺和蜜汁的比较转录组学和蛋白质组学。将在整个花朵成熟过程中对蜜腺进行RNA-SEQ，以便能够对色素合成途径进行比较挖掘，以及花蜜蛋白质鉴定，我们预测这将参与色素形成。3)确定色素形成机制。这一目标将表征花蜜蛋白在色素形成中的作用。4)启动花蜜色素的功能分析。花蜜色素可以作为传粉者的视觉提示。这一目标将评估彩色蜜汁是否对可疑的传粉者可见和明显。所有方法和数据集都将通过项目网站(www.nectarygenomics.org)和出版物公开提供。长期访问将通过建立的公共数据库提供。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nearly 90% of flowering plants produce floral nectar, the volume and composition of which have been correlated with the efficiency of animal-mediated pollination that impacts the production of 87 out of 115 (~76%) of the leading global food crops which represents an annual value of $29 billion in the U.S. alone and accounts for one-third of total food production. Although sugars are the predominant nectar solutes, ~10% of nectar dry weight is represented by many types of non-sugar solutes, including specialized metabolites, like pigments. Pigments play essential roles in biotic interactions throughout the Tree of Life, with natural pigments having a global market value of $5B annually. This project will use a comparative genomics interdisciplinary approach to test the central hypothesis that colored nectars contain novel and known pigments, which evolved from being selectively favored through having spectral qualities attuned to pollinator vision. The activities outlined in this study are wholly novel and will provide new insights into the biology of an essential plant-animal mutualism on a genome-wide scale by (1) systematically profiling nectar pigments across species; (2) determining to what extent nectaries can actively control non-sugar nectar content, with an emphasis on nectar pigments; (3) understanding how evolutionary and natural history impact nectar quality with respect to pigment content; (4) identifying and characterizing enzymes involved in pigment synthesis; and, (5) systematically evaluating the true biological functions of nectar pigments. With respect to broader impacts, the project will help train the next generation of plant biologists by providing research training experiences for undergraduate, graduate, and middle school students. In addition, the project will take advantage of the broad public interest in the conservation of plant:pollinator interactions through citizen science projects.Plant-pollinator interactions have at least partially driven the massive species radiation observed in the angiosperms, leading not only to extreme diversification in flower size and morphology, but also the accompanying chemistries behind attractants (color and scent) and rewards (nectar and pollen). Although rare, one floral trait that has evolved multiple times is colored nectar, which is suggested to serve as a visual cue of reward to prospective pollinators. Approximately 70 plant species are known to produce colored nectars, but the identities of these pigments, their associated syntheses, and true biological functions, have not yet been described. To address this gap in knowledge, the overarching goal of this project is to decipher the diversity, synthesis, and function of nectar pigments within a phylogenetic and evolutionary framework. The specific aims of this project include:1) Systematic identification of nectar pigments in 20+ taxa of diverse lineages via LC MS/MS, including multiple sister taxa with different colored nectars. 2) Comparative transcriptomics and proteomics of nectaries and nectars. RNA-seq will be conducted on nectaries throughout floral maturation to enable comparative mining of pigment synthesis pathways, as well as nectar protein identification, which we predict to be involved in pigment formation.3) Determine mechanisms of pigment formation. This aim will characterize the role of nectar proteins in pigment formation.4) Initiation of functional analyses of nectar pigments. Nectar pigments may serve as visual cues to pollinators. This aim will evaluate if colored nectars are visible and conspicuous to suspected pollinators. All methods and datasets will be made publicly available through the project website (www.nectarygenomics.org) and publications. Long-term access will be provided through established public data repositories.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.