Transcription Regulatory Circuits of Grass Cell Wall Biosynthesis

降解纤维素生物质的成本目前阻碍了其作为有竞争力的国内可再生燃料替代品的广泛使用。微生物对各种生物质资源的转化是一种很有前途的可再生液体燃料。该项目的目标是对控制生物量积累的基因有一个基本的了解。这将使我们能够实现生产生态和经济上可持续的生物燃料原料的长期目标。这项研究专门针对调控植物生长的一个关键方面的基因，即细胞壁的形成。在特定的细胞中，细胞壁非常厚，正是这些细胞壁占了所有植物生物量的大部分。草类包括许多我们最重要的食物和饲料作物，包括玉米、小麦、水稻、黑麦草和高羊茅。尽管植物细胞壁对植物生长很重要，但我们对细胞壁聚合物协同合成的精确调控机制的了解有限。对于草类来说尤其如此。该项目将为至少两名马萨诸塞大学的研究生提供发育、遗传学、基因组学和生物化学方面的跨学科培训，并促进国家聋人技术研究所的实习计划。本研究旨在了解调控禾本科植物次生细胞壁生物合成的转录网络。细胞壁是由多糖、蛋白质和木质素组成的复杂复合物。目前对细胞壁生物合成的转录调控的了解大部分来自拟南芥木质部导管和纤维的研究，但这种理解可能无法推广到陆地植物。禾本科植物的细胞壁，包括为人类提供大部分热量的驯化谷物和作为生物燃料能源作物开发的多年生植物，在形态和组成上与拟南芥（eudicot a.thaliana）有很大不同。本研究将探讨三种短柄柄柄柄远端粒转录因子：GRASS NAC REPRESSOR of开花（GNRF）、WALL REGULATOR INTERACTING bHLH （WRIB）、knot - like HOMEOBOX of Brachypodium DISTACHYON7 （KNOB7）的功能。研究人员假设，这些蛋白质通过蛋白质-蛋白质和蛋白质- dna的相互作用来调节壁生物合成，这些相互作用构成了一个受外部信号影响的前馈和负反馈循环系统。转录因子将通过染色质免疫沉淀等方法进行表征，以确定蛋白质的基因启动子靶点以及结合对细胞壁生物合成的影响。蛋白-蛋白相互作用将使用共免疫沉淀进行评估。光循环和热循环在细胞壁调节功能中的可能作用将通过测量不同突变背景下植物在不同时间过程条件下的功能来测试。

The costs of degrading cellulosic biomass currently impede its widespread use as a competitive domestic renewable alternative to fossil fuels. A promising route to renewable liquid fuels is the conversion of various biomass sources by microbial organisms. The goal for this project is to develop a basic understanding of the genes that control biomass accumulation. This will enable our long-term goal of producing ecologically and economically sustainable sources of feedstocks for biofuels. The research specifically addresses the genes that regulate a key aspect of plant growth, which is the creation of cell walls. In specific cells the walls are very thick and it is these that account for the bulk of all plant biomass. Grasses include many of our most important food and forage crops including maize, wheat, rice, ryegrass, and tall fescue. Despite the importance of the plant cell wall for plant growth, our knowledge of the precise regulatory mechanisms that give rise to the coordinated synthesis of the wall polymers is limited. This is especially true of grasses. This project will provide interdisciplinary training in development, genetics, genomics, and biochemistry for at least two University of Massachusetts graduate students and facilitate an internship program with the National Technical Institute for the Deaf.This proposal aims at understanding the transcription networks that regulate secondary cell wall biosynthesis in grasses. The cell wall is a complex composite of polysaccharides, proteins, and lignin. Much of what is currently understood about the transcriptional regulation of cell wall biosynthesis is from the study of Arabidopsis thaliana xylem vessels and fibers, yet this understanding may not be generalizable across land plants. The cell walls of grasses, including domesticated cereals that provide the majority of human calories and the perennials under development as biofuel energy crops, differ significantly in morphology and composition from the eudicot A. thaliana. The research will explore the function of three Brachypodium distachyon transcription factors: GRASS NAC REPRESSOR OF FLOWERING (GNRF), WALL REGULATOR INTERACTING bHLH (WRIB), KNOTTED-LIKE HOMEOBOX OF BRACHYPODIUM DISTACHYON7 (KNOB7). The researchers hypothesize that these proteins regulate wall biosynthesis through protein-protein and protein-DNA interactions that make-up a system of feed forward and negative feedback loops that are influenced by external cues. Transcription factors will be characterized by using methods such as chromatin immunoprecipitation to determine the gene promoter targets of the proteins and the effect of binding on cell wall biosynthesis. Protein-protein interactions will be evaluated using co-immunoprecipitation. A possible role for photo and thermocycles in the function of cell wall regulation will be tested by measuring function under varying time course conditions in plants of different mutant backgrounds.