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

植物产生各种化学化合物，这些化合物对制造细胞和整个生物体至关重要。 这些化合物之一，木质素，赋予植物物理强度并支持植物中的水分运输。 产生具有较少木质素的生物能源植物是有益的，因为木质素阻碍生物乙醇的生产。然而，降低木质素产量可能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中的基本过程如何演变来解决这一基本问题。 具体而言，该项目旨在了解负责在草中制造木质素的基因和途径，草是食物和生物能源生产的主要来源。因为草有一个独特的途径来制造木质素，这是在其他植物中没有发现的，了解这种草特异性木质素途径的演变将提供更好的策略，以改善草的有效生产粮食和能源。 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推广活动。“这将特别侧重于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，通过提高对植物中基本化合物（如木质素）的理解。初级代谢产物，如蛋白质和细胞壁，直接影响作物的产量，品质和性能。这项研究将探索初级代谢多样性，揭示植物代谢的主要进化创新，并提供新的工具和策略，以合理优化植物中的这些核心代谢过程。一种主要的细胞壁组分，木质素和其他酚类化合物通过芳香族氨基酸和苯丙素途径的复杂网络产生，通常由L-苯丙氨酸合成。独特的是，草另外从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物化学和遗传基础，酪氨酸衍生的木质素生物合成途径。利用丰富的基因组/转录组数据，从草和非草单子叶植物，该项目将采用“基因导向”的生化和基因组分析，解剖酪氨酸衍生的木质素生物合成途径和它们的进化历史。目的1）通过单子叶植物中关键酶的活性筛选，确定酪氨酸-木质素途径出现的进化时间。目的2）通过对这些酶的结构-功能分析，明确酪氨酸衍生木质素途径进化的分子基础。目标3）将进一步识别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）研究酪氨酸-木质素生物合成网络中关键酶的功能化。该研究将建立一个多学科的方法，遗传学引导的生化基因组学，这使我们能够调查复杂的性状的进化史，如初级代谢多样性，发生在多个位点在一个漫长的进化时间尺度。这个奖项反映了NSF的法定使命，并已被认为是值得支持的评估使用基金会的智力价值和更广泛的影响审查标准。

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.