Pollen apertures as a model for formation of distinct extracellular domains

在生物体中，细胞外物质在细胞旁边的沉积可以保护细胞，改变其生长和形态，或帮助其移动和与其他细胞交流。为了能够执行如此重要的功能，细胞外物质必须非常精确地沉积，但细胞如何实现这种精确性大多是未知的。一个非常精确的细胞外结构的例子是植物花粉周围的细胞壁。不同种的花粉粒外观往往有很大差异，部分原因是花粉表面的某些地方沉积有壁物质，而另一些地方则没有壁物质。没有花粉壁的地方称为孔，这些结构帮助花粉执行其生殖功能。不同物种之间，花粉孔的形状、数量和位置往往不同，但同一物种内的花粉孔模式通常是相同的。以花粉孔的形成为模型，该项目将研究细胞如何确定哪些表面区域将缺乏细胞外结构，以及这些区域的位置是如何标记的。了解花粉中的图案形成将提供对许多发育过程中图案形成的深入了解。 在这个项目的更广泛的影响，几个年轻的科学家将接受培训，工作的结果将通过讲座在艺术&科学本科课程，显微镜课程，and by interacting互动with middle中等and high高-在生物学增强讲习班和顶点实习计划的学校学生。细胞如何发展细胞外结构的精确定义的结构域是一个重要的，但知之甚少。问题花粉粒为研究这一问题提供了一个很好的模型，因为它们的表面被细胞壁（外壁）覆盖，细胞壁组装成不同的物种特异性模式。花粉壁保护花粉粒内的精细胞，并在植物繁殖中起着其他几个重要作用。除了外壁覆盖的区域外，大多数植物的花粉表面都有特征性的开口，或孔，外壁缺失或减少。这表明，在花粉发育过程中，在花粉表面形成特定的区域，这些区域被细胞壁沉积机制可靠地识别为不同于表面的其余部分，并且这些区域将成为孔。与外壁图案的情况一样，孔通常在物种之间变化很大，在它们的数量，位置和形态上不同，但在每个物种内，它们的图案都受到严格的发育控制。作为定义明确，严格监管，易于识别和量化的结构，孔提供了一个有吸引力的处理解决花粉表面图案形成的复杂问题，并可以作为一个强大的模型产生不同的细胞外结构域，一个过程中的重要的各种细胞和生物体。通过各种遗传学，细胞生物学和计算方法，并使用拟南芥花粉作为模型，该项目的目的是辨别孔径指定域是如何形成的，并定义孔径发展的重要细胞生物学事件。这将允许创建一个范例，植物细胞如何产生功能上不同的外周结构域，以及细胞壁沉积机制如何解释这些结构域，以产生细胞外差异。

In an organism, deposition of extracellular materials next to a cell can protect the cell, change its growth and morphology, or help it to move and communicate with other cells. To be able to perform such important functions, extracellular materials must be deposited very precisely, but how cells achieve such precision is mostly unknown. A beautiful example of an extracellular structure with a very precise deposition is the wall surrounding plant pollen. Pollen grains from different species often look remarkably different, in part, because wall materials are deposited at some places on pollen surface and absent from the others. The places where pollen wall is absent are called apertures, and these structures help pollen perform its reproductive function. Across species, pollen apertures often differ in shape, number, and positions, but within a species aperture patterns are usually the same. Using formation of pollen apertures as a model, this project will investigate how cells determine which surface areas will lack extracellular structures and how positions of such areas are marked. Understanding pattern formation in the context of pollen will provide insight into pattern formation during many developmental processes. In broader impacts of this project, several young scientists will be trained and the results of the work will be communicated to larger audiences through lectures in an Arts & Science undergraduate course, microscopy courses, and by interacting with middle- and high-school students during biology enhancement workshops and a Capstone internship program.How cells develop precisely defined domains of extracellular structures is an important and poorly understood question. Pollen grains provide an excellent model for studying this problem, as their surfaces are covered by the cell wall, exine, which assembles into diverse species-specific patterns. This wall protects sperm cells within the pollen grains and plays several other important roles in plant reproduction. In addition to the exine-covered areas, pollen surfaces of most plant species have characteristic openings, or apertures, where exine is absent or reduced. This indicates that, in the course of pollen development, specific domains are formed on pollen surface, which are reliably recognized by the cell wall deposition machinery as different from the rest of the surface and which will become apertures. As is the case with exine patterns, apertures often vary greatly across species, differing in their number, positions, and morphology, yet within each species their patterns are under tight developmental control. As well-defined, tightly regulated, and easily recognizable and quantifiable structures, apertures provide an attractive handle for addressing the complex problems of pollen surface pattern formation and can serve as a powerful model for generation of distinct extracellular domains, a process important in a wide variety of cells and organisms. Through a variety of genetic, cell-biological, and computational methods and using Arabidopsis pollen as a model, this project aims to discern how the aperture-specifying domains are formed and to define cell-biological events important for aperture development. This will allow creating a paradigm for how plant cells generate functionally distinct peripheral domains, and how cell wall deposition machinery interprets these domains to generate extracellular differences.