Uncovering the roles of NF-Y transcription factors in early photomorphogenesis

当我们考虑植物和阳光的关系时，我们自然会想到光合作用；毕竟，从小学开始，光合作用的重要性就被反复强调。不太为人所知的事实是，植物有非常复杂的光感知系统，这些系统与光合作用有关，但又与光合作用分开。这些系统使植物能够感知不断变化的光环境，并做出适当的发育“决定”，影响从何时发芽到生长模式和繁殖时间的一切。因此，发现这些光感知系统如何在机械上起作用，对于理解高度操纵的农业环境和更自然的生态系统中的植物是绝对必要的。许多科学家已经研究了这些过程，并且对特定的光感受器如何感知单个波长的光并在植物内部传递这些信息了解甚多。众所周知，对不同波长光的感知会导致基因表达的大量和快速变化，从而导致植物在视觉上明显的变化，例如远红光条件下茎伸长增加。霍尔特实验室最近发现了几个新的基因，它们调节光信号转化为基因表达变化的点。这项NSF的奖励将允许他们进一步探索这些功能的机制基础——也就是说，他们将把他们的发现过程从“谁”扩展到“如何”。拟议的研究将包括对博士后、研究生和本科生进行尖端遗传和生物化学研究的培训和指导。此外，PI还将参与一项针对即将进入科学专业的新生的年度指导计划，在每个资助年度接待两名夏季REU本科生，并将研究的各个方面纳入植物生理学的本科课程。虽然近年来我们对光信号通路的机制理解已经非常成熟，但有证据表明并非所有促进光形态发生的转录因子都已被确定。例如，远红光主要由phyA光感受器感知，这一途径终止于许多特征明确的转录因子的激活，特别是HFR1、HY5和LAF1。然而，即使这些基因的三重突变植物也不能完全再现phyA突变体或在黑暗中生长的植物的表型。核因子Y （NF-Y）转录因子最近被确定为几种光信号通路的附加组分，特别是远红光。此外，这些基因至少部分独立于HY5，如果不是完全独立的话。因此，该基金支持的主要研究目标是验证NF-Y转录因子调节先前未被描述的远红光信号通路的假设，该通路平行运行，但独立于已被描述的HFR1、HY5和LAF1转录因子。该项目的具体目标是直接测试这一假设，从机制上探索与蛋白酶体相关的NF-Y功能，并使用抑制因子筛选为光形态形成过程中NF-Y信号传导提供更广泛的背景。

When we consider the relationship between plants and sunlight, we naturally think about photosynthesis; after all, the importance of photosynthesis was repeatedly emphasized to most of us since grade school. Less well-understood is the fact that plants have very complex light perception systems that relate to, but are separable from photosynthesis. These systems allow plants to perceive their constantly changing light environment and make appropriate developmental "decisions", influencing everything from when to germinate to the patterns of growth and the timing of reproduction. Thus, discovering how these light perception systems mechanistically function is absolutely essential for understanding plants in both highly manipulated agricultural settings and more natural ecosystems. Many scientists have investigated these processes and much is known about how specific photoreceptors perceive individual wavelengths of light and relay this information within the plant. It is well-understood that perception of different wavelengths of light causes massive and rapid alterations in gene expression, resulting in visually obvious changes to the plant, such as increased stem elongation in far red light conditions. The Holt Lab recently discovered several new genes that regulate the point at which light signals are turned into changes in gene expression. This NSF award will allow them to further explore the mechanistic basis for these functions - i.e., they will extend their discovery process from the "who" to the "how". The proposed research will include training and mentoring of postdocs, graduate students and undergraduate students in cutting edge genetic and biochemical research. Additionally, the PI will participate in an annual freshman mentoring program for incoming science majors, host two summer REU undergraduate students in each funded year, and incorporate aspects of the research into an undergraduate course in plant physiology.While our mechanistic understanding of light signaling pathways has matured greatly in recent years, there is evidence that not all of the photomorphogenesis-promoting transcription factors have been identified. For example, far red light is primarily perceived by the phyA photoreceptor and this pathway terminates in the activation of a number of well-characterized transcription factors, in particular HFR1, HY5, and LAF1. However, even triple mutant plants for these genes do not fully recapitulate the phenotypes of phyA mutants or plants grown in the dark. NUCLEAR FACTOR Y (NF-Y) transcription factors were recently identified as additional components of several light signaling pathways, especially far red light. Additionally, these genes appear to signal at least partially, if not completely, independent of HY5. Thus, the principal research objective supported by this funding is to test the hypothesis that NF-Y transcription factors regulate a previously non-described far red light signaling pathway, operating in parallel, but independent to the well-described HFR1, HY5, and LAF1 transcription factors. The specific aims of the project are directed towards directly testing this hypothesis, mechanistically exploring NF-Y function related to the proteasome, and use of a suppressor screen to provide a broader context for NF-Y signaling during photomorphogenesis.