Molecular genetic investigation of land plant gravity signaling

大约4亿年前，当植物在陆地上定居时，它们进化出了利用地球引力矢量来引导根和芽生长的能力。潜在的重力感应和响应系统还没有被很好地理解，尽管通过选择性育种对其进行了修改，重要地塑造了今天的作物植物和树木，未来的生产力增长预计将通过修改，从而使根系更陡峭，能够更好地到达水源，当植物在高密度生产场景中拥挤时，枝条的角度能更好地拦截光线。本项目旨在鉴定由基因编码的蛋白质，这些蛋白质构成了拟南芥植物的重力感应机制，这是植物的一般模型。该项目建立在研究表明，只有在陆地植物中发现的少数LAZY基因编码了定向根和芽的重力信号系统的关键组成部分的基础上。该项目将使用遗传学和生物化学领域的实验方法来寻找与LAZY蛋白一起起作用的基因及其蛋白质，从而在细胞内创建一条途径，将重力矢量转化为引导生长的生理变化。对这条通路的结构和功能的更清晰的认识将显示植物如何解决在陆地上生活的挑战，并将为改善作物植物结构提供机会。外展活动将向年轻市民介绍对重力的反应。实验计划包括三个部分。第一种是基于抑制惰性四重突变体严重向重力生长的突变。惰性四重体（slq）的一个抑制基因已经被发现，另一个正在进行基因定位。SLQ1负调控LAZY功能。我们将研究SLQ1的表达模式、亚细胞定位和作用机制，其他slq在确定后也将进行类似的研究。另一部分是基于LAZY1和在酵母双杂交（Y2H）筛选中发现的一种名为BRXL4的蛋白质之间的功能相关相互作用。Y2H方法将用于寻找额外的交互作用者。蛋白质组学筛选可以独立鉴定LAZY1相互作用体。在整个项目中使用不同的方法是为了增加获得收敛结果的可能性。例如，在slq突变筛选中发现的基因可能编码与LAZY1物理相互作用的蛋白质。基因、细胞和生物化学的结果将结合起来创建一个重力信号框架。第三部分将测试框架的机制元素。该项目预计将建立一个前所未有的分子细节水平，了解植物如何利用重力矢量来指导生长。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。

As plants colonized land some 400 million years ago, they evolved the ability to orient the growth of their roots and shoots using the Earth’s gravity vector as a guide. The underlying gravity sensing and response system is not well understood, even though modification of it through selective breeding has importantly shaped today’s crop plants and trees, and future gains in productivity are expected to attend modifications that result in steeper roots better able to reach water sources, and shoots with angles that intercept light better when plants are crowded in high-density production scenarios. This project aims to identify the proteins, which are encoded by genes, that make up the gravity sensing mechanism in the Arabidopsis thaliana plant, which is a model for plants in general. The project builds off of research indicating that a small number of LAZY genes, found only in land plants, encode key components of the gravity signaling system that orients roots and shoots. The project will use experimental methods from the fields of genetics and biochemistry to find genes and their proteins that function with LAZY proteins to create a pathway within cells that translates the gravity vector into a physiological change that steers growth. A clearer view of this pathway’s structure and function will show how plants solved a challenge to living on land, and it will generate opportunities to improve crop plant architecture. Outreach activities will introduce young members of the public to plant responses to gravity.The experimental plan consists of three sections. The first is based on mutations that suppress the severely agravitropic growth of a lazy quadruple mutant. One of the suppressor of lazy quadruple (slq) mutants has been identified, one more is being genetically mapped. SLQ1 negatively regulates LAZY function. SLQ1 expression pattern, subcellular localization, and mechanism of action will be studied, Other SLQs will be similarly studied after they are identified. Another section is based on a functionally-relevant interaction between LAZY1 and a protein called BRXL4 discovered in a yeast two-hybrid (Y2H) screen. The Y2H method will be used to find additional interactors. A proteomic screen will independently identify LAZY1 interactors. Separate approaches used throughout the project are designed to increase the probability of obtaining convergent results. For example, genes identified in a screen for slq mutations may encode proteins that interact physically with LAZY1. The genetic, cellular, and biochemical results will be combined to create a gravity signaling framework. A third section will test mechanistic elements of the framework. The project is expected to establish an unprecedented level of molecular detail about how plants use the gravity vector to guide 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.