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

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

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.