Arabidopsis 2010: Functional Analysis of Pollen Exine Assembly

该项目将确定构建外花粉壁(外壁)所需的基因。外壁无与伦比的强度和耐化学性对花粉的存活很重要。这一壁在雌雄细胞之间的相互作用中也起着重要的作用：外壁是花粉和花的雌性器官之间发生物种特异性黏附所必需的。Exine是由孢粉蛋白组成的，这是一种异常强大的、化学上惰性的、具有独特图案的生物聚合物，可能会被证明对材料科学行业有用。因此，它在授粉中的重要性，对聚合物化学的影响，以及作为接触粘合剂的用途，使得对其组成的了解变得高度优先。外壁的惰性和不规则性给化学分析带来了混乱，但最近的拟南芥遗传研究更有希望，揭示了外壁结构和功能所需的基因和途径。普赖斯、萨姆纳、埃德伦德和斯旺森实验室的工作将扩展这些努力。该项目致力于2010年的项目目标，即对每个拟南芥基因进行功能分析。它将评估特定基因在外壁组装、构图和黏附中的作用，并将这些基因分类为遗传和新陈代谢途径。建立正常外壁形态所需的拟南芥基因将通过对候选基因中约250个插入的可视特征以及对新突变体的大规模筛选来定义。目标基因选自a)在外壁合成中起作用的生物合成途径；b)在外壁合成中具有未确定作用的途径；c)与外壁发育中已知功能相似的基因；d)其表达模式表明它们可能在花粉发育过程中活跃在花药中的基因。正在研究的基因和研究进展将在http://preuss.bsd.uchicago.edu/nsf2010.html.上公布。数据一般每半年发布一次。对于每个已确定的突变体，将使用显微镜和生化分析来表征突变基因的作用。遗传和生化网络将通过表征外壁基因表达的时间，检查花粉发育过程中代谢物的积累，以及分析双突变体来阐明。这项工作将影响多个学科，提高对1)介导授粉和作物育种的基因，2)对外壁多样性和植物物种形成的进化控制，3)生物聚合物自组装，使研究人员能够概括体外培养外壁发育的酶步骤，最终导致设计具有所需特征的外壁，4)促进花粉附着的外壁部分，可能合成高度特异的接触粘合剂，5)250个基因，可能在外壁发育中发挥作用的理解。教育和人员培训将是该项目不可或缺的一部分。将培训两名技术员和至少四名本科生(包括两名来自斯佩尔曼大学和瓦尔帕莱索大学的本科生)。学生，包括那些历史上在科学领域代表性不足的学生，将有机会进行暑期研究，发展他们在规划和执行实验方面的经验，并在研究会议上展示他们的工作。他们的导师将生成信息，并将其纳入他们的实验室和课程。此外，博士后研究员将通过指导技术人员和本科生接受研究和指导方面的培训，使他们能够过渡到独立的职业生涯。

This project will identify genes required to construct the outer pollen wall (exine). The unparalleled strength and chemical resistance of exine is important for pollen survival. This wall also plays an important role in interactions between male and female cells: exine is required for the species-specific adhesion that takes place between pollen and the female organs of the flowers. Exine is made of sporopollenin, an unusually strong, chemically inert and distinctively patterned biopolymer that may prove useful for the materials science industry. Thus, its importance in pollination, implications for polymer chemistry, and utility as a contact adhesive make an understanding of its composition a high priority. The inert and irregular nature of exine has confounded chemical analysis, but recent Arabidopsis genetic surveys are more promising, revealing genes and pathways required for exine structure and function. The work of the Preuss, Sumner, Edlund, and Swanson labs will extend these efforts. This project addresses the 2010 program goal of functional analysis of every Arabidopsis gene. It will assess the role of specific genes in exine assembly, patterning and adhesion, and will sort these genes into genetic and metabolic pathways. Arabidopsis genes required for establishing normal exine morphology will be defined by visually characterizing ~250 insertions in candidate genes, as well as by performing a large-scale screen for novel mutants. The targeted genes are selected among a) biosynthetic pathways previously implicated by chemical or genetic analyses as playing a role in exine synthesis; b) pathways with an unresolved role in exine synthesis; c) genes resembling those with a known function in exine development; d) genes, whose expression pattern indicates they are likely active in anthers during pollen development. The genes under study and progress of the research will be available at http://preuss.bsd.uchicago.edu/nsf2010.html. Data will be released generally on a semi-annual basis. For each of the mutants identified, microscopic and biochemical assays will be employed to characterize the roles of the mutated genes. Genetic and biochemical networks will then be clarified through characterizing the timing of exine gene expression, examining metabolite accumulation during pollen development, and analyzing double mutants. This work will impact multiple disciplines, improving the understanding of 1) genes that mediate pollination and crop breeding, 2) evolutionary control over exine diversity and plant speciation, 3) biopolymer self-assembly to allow investigators to recapitulate enzymatic steps of exine development in vitro, ultimately resulting in designing exine walls with desired characteristics, 4) exine moieties that contribute to pollen adhesion, possibly allowing the synthesis of highly specific contact adhesives, 5) 250 genes that could play a role in exine development. Education and personnel training will be an integral part of this project. Two technicians and at least 4 undergraduates (including 2 from the primarily undergraduate institutions - Spelman and Valparaiso) will be trained. Students, including those historically underrepresented in science, will have an opportunity for summer research, developing their experience in planning and performing experiments and presenting their work at research conferences. Their mentors will generate information to incorporate in their laboratories and courses. In addition, postdoctoral fellows will be trained in research and mentoring via supervising technicians and undergraduates, enabling transitions to independent careers.