权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Protein Glycosylation in Pollen Tube Growth and Fertilization

花粉管生长和受精中的蛋白质糖基化

基本信息

批准号：
1755482
负责人：
Cora MacAlister
金额：
$ 60.08万
依托单位：
Regents of the University of Michigan - Ann Arbor
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-03-15 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1755482&HistoricalAwards=false
关键词：
Protein Glycosylation Pollen Tube Growth

项目摘要

The majority of food crops are flowering plants that require successful fertilization to produce grains and fruits. Fertilization requires pollen to land on the female flower and form a pollen tube, a rapidly elongating single-celled projection which grows through the female tissue, in some cases for several centimeters. This pollen tube is able to reorient its growth in response to chemical guidance cues to deliver the male reproductive cells to the female. The pollen tube, like other plant cells is surrounded by a cell wall and cell expansion requires the proper secretion of new cell wall material that is specifically targeted to the specialized, flexible cell wall at the growing tip. The internal secretory machinery and the cell wall must be appropriately coordinated with each other and with the direction of elongation for successful sustained growth. Despite the importance of this process for agricultural production, a major gap exists in our understanding of how the external cell wall and the intracellular secretory apparatus coordinate to maintain a stable but responsive tip region over time. This project will elucidate the linkage between these two compartments using genetics, biochemistry and cell imaging approaches. The research will also support the training of graduate and undergraduate students. Research activities will be integrated into an introductory plant biology lab course giving students an authentic research experience. In addition, the project will provide interactive, hands-on activities to the general public in collaboration with the University of Michigan Museum of Natural History. This project was co-funded by the Plant, Fungal and Microbial Developmental Mechanisms Program in the Division of Integrative Organismal Systems and the Cellular Dynamics and Function Program in the Division of Molecular and Cellular Biosciences. Flowering plant fertility depends on the sustained rapid elongation of pollen tubes and their ability to reorient growth to effectively target receptive ovules. Proper pollen tube elongation requires hydroxyproline (hyp) O-arabinosylation, the posttranslational addition of arabinose sugar chains to hydroxyprolines. Arabinosyltransferase mutants exhibit shorter, wider and sometimes branched pollen tubes, suggesting impaired tip-region stability. The secretion required for pollen tube elongation depends on the highly dynamic F-actin structures at the pollen tube tip. F-actin organization is controlled, in part, by the nucleation activity of class 1 formin homology proteins. The extracellular domains of these proteins contain predicted arabinosylation motifs which have been implicated in interaction with the cell wall. This project will test the hypothesis that the pollen tube cell wall and actin cytoskeleton are coordinated via hyp O-arabinosylation of the class 1 formin homology proteins, limiting their actin organizing activity to appropriate cortical domains though interaction with the overlying cell wall. Altered cell wall polarity and actin organization will be assayed in the mutants and wild type. The in vivo glycosylation status of the class 1 formins will be determined for three important members of this protein family, including two known regulators of pollen tube actin. Furthermore, the effect of the extracellular domains on protein mobility and localization in the pollen tube will be determined. This research will establish an essential point of connection between two major cell components required for pollen tube polarization and growth.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.

大多数粮食作物都是开花植物，需要成功的施肥才能产生谷物和水果。受精需要花粉落在雌花上并形成花粉管，花粉管是一种快速伸长的单细胞突起，穿过雌花组织生长，有时长达几厘米。这个花粉管能够根据化学引导信号重新调整其生长方向，将雄性生殖细胞传递给雌性。像其他植物细胞一样，花粉管被细胞壁包围，细胞的扩张需要适当地分泌新的细胞壁物质，这些物质专门针对生长尖端的特殊的、灵活的细胞壁。内部分泌机制和细胞壁必须适当地相互协调，并与伸长的方向协调，才能成功地持续生长。尽管这一过程对农业生产很重要，但我们对细胞外壁和细胞内分泌装置如何协调维持一个稳定但反应灵敏的尖端区域的理解存在重大差距。本项目将利用遗传学、生物化学和细胞成像方法阐明这两个区室之间的联系。这项研究也将支持研究生和本科生的培养。研究活动将整合到植物生物学入门实验课程中，让学生获得真实的研究体验。此外，该项目还将与密歇根大学自然历史博物馆合作，为公众提供互动的实践活动。该项目由综合生物系统部的植物、真菌和微生物发育机制项目和分子与细胞生物科学部的细胞动力学和功能项目共同资助。开花植物的育性取决于花粉管的持续快速伸长及其重新定向生长的能力，以有效地靶向受感胚珠。正确的花粉管伸长需要羟脯氨酸（hyp） o -阿拉伯糖基化，翻译后将阿拉伯糖链添加到羟脯氨酸上。阿拉伯糖基转移酶突变体的花粉管更短、更宽，有时还会出现分枝，这表明花粉管端区稳定性受损。花粉管伸长所需的分泌取决于花粉管尖端高度动态的f -肌动蛋白结构。在某种程度上，f -肌动蛋白的组织是由1类双胍同源蛋白的成核活性控制的。这些蛋白的胞外结构域含有预测的阿拉伯糖基化基序，这些基序与细胞壁相互作用有关。该项目将测试花粉管细胞壁和肌动蛋白细胞骨架通过1类双胍同源蛋白的低0 -阿拉伯糖基化进行协调的假设，通过与上盖细胞壁的相互作用，将其肌动蛋白组织活性限制在适当的皮质区域。细胞壁极性和肌动蛋白组织的改变将在突变体和野生型中进行检测。1类成形蛋白的体内糖基化状态将被确定为该蛋白家族的三个重要成员，包括两个已知的花粉管肌动蛋白调节因子。此外，细胞外结构域对花粉管中蛋白质迁移和定位的影响将被确定。本研究将建立花粉管极化和生长所需的两个主要细胞成分之间的重要连接点。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。