MCA-PGR: Phylogeny-Guided Biochemical Genomics to Elucidate the Tyrosine-Derived Lignin Metabolic Network of Grasses

植物产生各种化合物，这些化合物对制造细胞和整个生物体都是必不可少的。其中一种化合物，木质素，赋予植物体力并支持水分运输。由于木质素会阻碍生物乙醇的生产，因此产生较少木质素的生物能源植物是有益的。然而，降低木质素产量可能会对植物生长产生负面影响。这项研究将通过研究木质素等基本化合物是如何合成的以及不同植物的潜在过程是如何进化的来解决这一基本问题。具体来说，该项目旨在了解负责在草中制造木质素的基因和途径，这是食物和生物能源生产的主要来源。由于草具有其他植物所没有的独特的木质素制造途径，了解这种草特有的木质素途径的进化将为提高草的食物和能源生产效率提供更好的策略。为了提高人们对植物衍生化合物重要性的认识，并培养下一代科学家，该项目将开展名为“颜料艺术+”的K-12外展活动。这将特别关注来自科学代表性不足的社区的学校。该项目的科学和教育成果将对研究和社会产生广泛的影响，通过提高对基本化合物（如木质素）如何在植物中产生的理解。初级代谢物，如蛋白质和细胞壁，直接影响作物的产量、质量和生产性能。本研究将探索植物主要代谢多样性，揭示植物代谢的重大进化创新，并为合理优化这些核心代谢过程提供新的工具和策略。细胞壁的主要成分木质素和其他酚类化合物是通过芳香氨基酸和苯丙类途径的复杂网络产生的，通常由l -苯丙氨酸合成。独特的是，草还能从l -酪氨酸合成木质素。本研究旨在阐明这种独特的初级代谢多样化的生化和遗传基础，酪氨酸衍生的木质素生物合成途径。利用来自草和非草单子叶植物的丰富的基因组/转录组数据，该项目将采用“系统发育指导”的生化和基因组分析来剖析酪氨酸衍生的木质素生物合成途径及其进化史。目的1)将通过对单子叶植物中关键酶的活性筛选来确定酪氨酸-木质素途径出现的进化时间。目的2)将通过对这些酶的系统发育引导的结构-功能分析来确定酪氨酸衍生木质素途径进化的分子基础。目的3)将进一步确定共同进化和重塑整个酪氨酸-木质素生物合成网络的基因和酶。目的4)阐明参与酪氨酸-木质素生物合成网络的关键酶的潜在功能化。本研究将建立一个多学科的系统发育指导的生化基因组学方法，使我们能够研究复杂性状的进化史，如初级代谢多样性，发生在多个位点，在漫长的进化时间尺度。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。

Plants produce a variety of chemical compounds that are essential for making cells and the entire organism. One of these compounds, lignin, gives physical strength and supports water transport in plants. It is beneficial to generate bioenergy plants with less lignin because lignin impedes the production of bioethanol. However, lowering lignin production may negatively impact plant growth. This research will address this fundamental issue by studying how essential compounds such as lignin are synthesized and how the underlying processes evolved in different plants. Specifically, this project seeks to understand the genes and pathways responsible for making lignin in grasses, which are major sources of food and bioenergy production. Because grasses have a unique pathway for making lignin that is not found in other plants, understanding the evolution of this grass-specific lignin pathway will provide better strategies to improve grasses for efficient production of food and energy. To increase the awareness of the importance of plant-derived compounds and to train next generations of scientists, this project will conduct K-12 outreach activities called "Pigment Art+." This will be specifically focused on schools from communities that are underrepresented in science. The scientific and educational outcomes of this project will have broad impacts for both research and society through improved understanding of how essential compounds, such as lignin, are made in plants. Primary metabolites, such as proteins and cell walls, directly impact yield, quality, and performance of crops. This research will explore primary metabolic diversity to uncover major evolutionary innovations of plant metabolism and to provide novel tools and strategies to rationally optimize these core metabolic processes in plants. A primary cell wall component, lignin, and other phenolic compounds are produced through a complex network of the aromatic amino acid and phenylpropanoid pathways and usually synthesized from L-phenylalanine. Uniquely, grasses synthesize lignin additionally from L-tyrosine. This research aims to elucidate biochemical and genetic basis of this unique diversification of primary metabolism, the tyrosine-derived lignin biosynthetic pathway. Utilizing the wealth of genome/transcriptome data from grass and non-grass monocots, this project will employ "phylogeny-guided" biochemical and genomic analyses to dissect the tyrosine-derived lignin biosynthetic pathways and their evolutionary history. Aim 1) will determine the evolutionary timing of the emergence of the tyrosine-lignin pathway through activity screening of key enzymes across monocots. Aim 2) will define molecular basis of the evolution of the tyrosine-derived lignin pathway through phylogeny-guided structure-function analyses of these enzymes. Aim 3) will further identify genes and enzymes that co-evolved and reshaped the overall tyrosine-lignin biosynthetic network. Aim 4) will elucidate potential functionalization of key enzymes involved in the tyrosine-lignin biosynthetic network. This study will establish a multidisciplinary approach of phylogeny-guided biochemical genomics, which allows us to investigate evolutionary history of complex traits, such as primary metabolic diversity, that occurred in multiple loci over a long evolutionary time scale.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.