Comparative Analysis of C3 and C4 Leaf Development in Rice, Sorghum and Maize

主要研究者：Timothy纳尔逊，耶鲁大学联合PI：博伊斯汤普森研究所的托马斯布鲁特内尔;康奈尔大学的克拉斯货车维克;康奈尔大学的罗伯特特金;康奈尔大学的孙奇;刘鹏，爱荷华州州立大学C4型植物，如玉米、高粱和几种有前途的生物燃料原料，具有一系列复杂的性状，大大提高了它们的固碳、水和氮利用效率，以及在高温和光照强度下的性能，与C3型植物如水稻和许多温带草相比。关键的C4性状是（1）两种光合细胞类型（叶肉和维管束鞘）在碳固定和光合作用方面的特化和协作，（2）协作细胞之间代谢物的增强的运动，和（3）非常高的叶片脉序密度。这些C4性状似乎是监管功能的增强已经存在于效率较低的C3植物，但在不同的模式调节。尽管C4植物在不同的分类群中独立进化了至少50次，但对关键C4性状的分子基础的理解还不足以将其引入重要的C3植物以提高其作为农业或生物燃料原料的性能。该项目将比较水稻（C3草），玉米（中等C4草）和高粱（极端C4草）的叶子。基因转录物、蛋白质和代谢物的丰度和谱将沿着从叶基部的未成熟组织到叶尖的成熟组织的发育梯度进行沿着比较。为了对齐这三个物种的梯度，将采用基因表达、蛋白质积累、库-源转换和细胞壁特化的发育时间点的标记。将通过激光显微切割从每个叶阶段获得叶肉和维管束鞘细胞，并对其全基因组RNA转录物、蛋白质组（包括修饰）和选定的代谢物（与光合作用相关）进行分析和比较。通过对相应的C3和C4植物数据集的比较分析，将测试两个假设：（1）为了产生C4性状，植物使用已经存在于C3植物中的基因、蛋白质和代谢物的网络，以及（2）C4特征是可塑的，并且在一定程度上取决于环境和发育阶段。这项分析应确定的监管点，C3 species.Established和成功的暑期实习计划（http：//bti.cornell.edu/pgrp/，http：//www.yale.edu/stars/）的C4性状的生产的潜在目标将被用来参与本研究的本科生代表性不足的群体。PI/Co-PI还将参加高中教师课程开发研讨会。来自纽约和康涅狄格州的教师将参加为期一周的讲座和讨论，向他们介绍植物基因组学工具和技术。 这些教师将与康奈尔大学校园的植物科学教师合作，为课堂开发基于基因组学的模块。 针对高中教师，而不是学生本身，将极大地扩展该计划的覆盖范围，并将实现NSF的主要使命：向社会传达植物基因组研究成果的重要性。项目成果将通过特定项目的公共网站（C3-C4DB，http://c3c4.tc.cornell.edu）提供，并纳入Gramene公共数据库（http：www.gramene.org）。数据也将存放在NCBI http://www.ncbi.nlm.nih.gov/和EBI http://www.ebi.ac.uk/。 康奈尔大学开发的教学模块将通过http://bti.cornell.edu/pgrp/pgrp.php?提供id=601。

PI: Timothy Nelson, Yale UniversityCo-PIs: Thomas Brutnell, Boyce Thompson Institute; Klaas van Wijk, Cornell University;Robert Turgeon, Cornell University; Qi Sun, Cornell University; Peng Liu, Iowa State UniversityC4-type plants such as maize, sorghum and several promising biofuel feedstocks possess a set of complex traits that greatly enhance their efficiency of carbon-fixation, water and nitrogen use, and performance in high temperatures and light intensities, in comparison to C3-type plants such as rice and many temperate grasses. The key C4 traits are (1) specialization and cooperation of two leaf photosynthetic cell types (mesophyll and bundle sheath) for carbon fixation and photosynthesis, (2) enhanced movement of metabolites between cooperating cells, and (3) very high density of leaf venation. These C4 traits appear to be regulatory enhancements of features already present in less-efficient C3 plants, but regulated in different patterns. Although C4 plants have evolved at least 50 times independently in various taxonomic groups, the molecular basis of key C4 traits is insufficiently understood to permit their introduction into important C3 plants to enhance their performance as agricultural or biofuel feedstocks. This project will compare the leaves of rice (a C3 grass), maize (a moderate C4 grass) and sorghum (an extreme C4 grass). The abundance and spectrum of gene transcripts, proteins and metabolites will be compared along a developmental gradient from immature tissues at leaf base to mature tissues at the leaf tip. To align the gradients of the three species, markers for developmental time points in gene expression, protein accumulation, sink-source transition and cell wall specialization will be employed. Mesophyll and bundle sheath cells will be obtained from each leaf stage by laser microdissection, and their whole genome RNA transcripts, proteomes (including modifications), and selected metabolites (related to photosynthesis) will be profiled and compared. Two hypotheses will be tested by the comparative analysis of the corresponding C3 and C4 plant datasets: (1) To produce C4 traits, plants use networks of genes, proteins, and metabolites that are already present in C3 plants, and (2) C4 features are plastic and expressed in a degree that depends on environment and developmental stage. This analysis should identify the regulatory points that are potential targets for the production of C4 traits in C3 species.Established and successful summer internship programs (http://bti.cornell.edu/pgrp/, http://www.yale.edu/stars/) will be used to involve undergraduates from under-represented groups in this research. PI/Co-PIs will also participate in curriculum development workshops for high school teachers. Teachers from New York and Connecticut will participate in a one-week program of lectures and discussions to introduce them to plant genomics tools and technologies. These teachers will work with plant science faculty on the Cornell campus to develop genomics-based modules for the classroom. Targeting high school teachers, rather than the students themselves, will greatly extend the reach of this program and will fulfill a primary mission of the NSF: to communicate the significance of the outcomes of plant genome research to society.The project outcomes will be available through a project-specific public website (C3-C4DB, http://c3c4.tc.cornell.edu), and curated into the Gramene public database (http://www.gramene.org). Data will also be deposited at NCBI http://www.ncbi.nlm.nih.gov/ and EBI http://www.ebi.ac.uk/. Teaching modules developed at Cornell will be available through http://bti.cornell.edu/pgrp/pgrp.php?id=601.