Cues and mechanisms of daily cell wall thickening

大多数植物生物质是由包围某些类型细胞的厚壁组成的。树干或玉米杆大多是这种形式的次生细胞壁。这种植物质量增加的生长与导致植物体积变化的生长类型不同，植物体积变化是细胞大小变化的结果。体积增长的速率经常在一天中变化，其中茎可能在夜晚结束时比一天中的任何其他时间更快地伸长。植物对温度和光照的日常变化做出反应，它们的生物钟在协调这些节奏的时间方面发挥着作用。本项目的目标是了解控制细胞壁质量合成的环境线索和调节机制。植物细胞壁生物质是一种丰富的可再生资源，是纸浆和造纸、木材和纺织以及木质纤维素生物燃料工业的基石。所获得的知识将使传统育种和生物技术方法能够改善生态和经济上可持续的林业和农业的生产。该项目还将为研究生提供发育、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。该项目要求遗传和生物化学的方法来了解环境条件和控制模式草二穗短柄草细胞壁生物合成的时间的分子机制。本研究提出了三个综合假设：（1）次生壁生物合成是一种时间特异性行为。几个观察结果支持一个模型，在草细胞伸长和壁增厚的速度是相反的定时和每日温度变化的影响。将对植物生物量积累、聚合物前体代谢物和细胞壁基因表达的速率进行定量。(2)基因启动子序列决定次生细胞壁基因表达的时间。虽然已经报道了几种调节壁生物合成的特定蛋白质-DNA相互作用，但这些序列的存在对基因表达时间的功能结果仍然未知。这些DNA序列的特异性功能将在体内用合成启动子和天然启动子使用荧光素酶报告基因的实时监测进行研究。(3)光敏色素蛋白在一天中特定时间的细胞壁增厚中发挥作用。光敏色素蛋白二聚体是可逆的活性和非活性的，并且该过程的速率受红光/远红光比率和温度的影响。这一机制可能在次生细胞壁基因表达和细胞壁增厚节律的调控中发挥作用。野生型B。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Most plant biomass is made up of a thick wall that surrounds some types of cell. A tree trunk or a corn stalk are mostly this form of secondary cell wall. This growth, where plants increase in mass, is distinct from the type of growth that results in changes in plant volume which is the result of changes in cell size. The rate of volume growth often changes throughout the day, where stems may elongate much more rapidly at the end of the night than any other time of day. Plants respond to daily changes in temperature and light and their circadian clocks play a role in orchestrating the timing of those rhythms. The goal of this project is to understand the environmental cues and regulatory mechanisms that control the synthesis of cell wall mass. Plant cell wall biomass is an abundant renewable resource and the cornerstone to the pulp and papers, timber and textile, and lignocellulosic biofuel industries. The knowledge gained will enable conventional breeding and biotechnology approaches to improve the production of ecologically and economically sustainable forestry and agriculture. This project will also provide interdisciplinary training in development, genetics, genomics, and biochemistry for graduate students and facilitate an internship program with the National Technical Institute for the Deaf. This project calls for genetic and biochemical approaches to understand the environmental conditions and the molecular mechanisms that control the timing of cell wall biosynthesis in the model grass Brachypodium distachyon. Three integrated hypotheses will be pursued: (1) Secondary wall biosynthesis is a time-of-day specific behavior. Several observations support a model in grasses where the rate of cell elongation and wall thickening is inversely timed and influenced by daily changes in temperature. Rates of plant biomass accumulation, polymer precursor metabolites, and cell wall gene expression will be quantified. (2) Gene promoter sequences determine the timing of secondary cell wall gene expression. Although several specific protein-DNA interactions that regulate wall biosynthesis have been reported, the functional outcome of the presence of these sequences has on the timing of gene expression remains unknown. The specific function of these DNA sequences will be investigated in vivo with synthetic promoters and native promoters using real-time monitoring of luciferase reporters. (3) Phytochrome proteins play a role in time-of-day specific cell wall thickening. Phytochrome protein dimers are reversibly active and inactive, and the rate of that process is influenced by red/far-red light ratios and by temperature. This mechanism may play a role in the regulation of secondary cell wall gene expression and wall thickening rhythms. Wildtype B. distachyon and phytochrome mutants will be examined for the effects of red/far-red light and temperature on stem secondary wall thickness and associated gene expression.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.