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，我们大多数人就一再强调光合作用的重要性。人们不太了解的事实是，植物有非常复杂的光感知系统，这些系统与光合作用有关，但与光合作用是分开的。这些系统允许植物感知它们不断变化的光环境，并做出适当的发展“决定”，影响从何时发芽到生长模式和繁殖时机的一切。因此，发现这些光感知系统是如何机械运作的，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，关于特定的光感受器如何感知单个光的波长并在植物中传递这一信息，人们已经知道了很多。众所周知，对不同波长的光的感知会导致基因表达的大规模和快速变化，导致植物在视觉上明显的变化，例如在远红光条件下茎伸长增加。霍尔特实验室最近发现了几种新的基因，它们可以调节光信号转化为基因表达变化的时间点。这一NSF奖项将允许他们进一步探索这些功能的机械基础--即，他们将把发现过程从“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将参加针对理科专业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本科课程。虽然我们对光信号通路的机制理解在最近几年已经非常成熟，但有证据表明，并不是所有促进光形态建成的转录因子都被识别出来。例如，远红光主要被PhyA光感受器感知，这一途径终止于一些特征良好的转录因子的激活，特别是HFR1、HY5和LAF1。然而，即使这些基因的三倍突变植物也不能完全概括PhyA突变株或在黑暗中生长的植物的表型。核因子Y(NF-Y)转录因子是近年来发现的几种光信号通路的附加成分，尤其是远红光。此外，这些基因似乎至少部分地(如果不是完全)发出信号，与HY5无关。因此，这笔资金支持的主要研究目标是检验这一假设，即核因子-Y转录因子调控先前未描述的远红光信号通路，平行操作，但独立于已描述的HFR1、HY5和LAF1转录因子。该项目的具体目标是直接测试这一假说，机械地探索与蛋白酶体相关的NF-Y功能，并使用抑制屏幕为光形态发生过程中的NF-Y信号提供更广泛的背景。

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.