Intellectual merit. How plants perceive and transduce hormone signals to effect dramatic changes in form and function is a fundamental question in biology that also has important practical applications. The response to ethylene gas continues to serve as a paradigm for understanding the mechanisms of plant hormone signal transduction. Ethylene plays critical roles in development, such as in the ripening of fruits and in responses to a variety of physical and biological stresses, such as pathogen attack. In order to understand the molecular mechanisms that underlie these biological processes, genetic, molecular, biochemical, genomic and cell biological approaches will be employed using the reference plant Arabidopsis thaliana. In particular, the goal of this research is to characterize the functions of the key positive regulator in the ethylene signaling pathway: EIN2. EIN2 is an ER-located integral membrane protein whose levels are regulated by ethylene-dependent proteosome degradation. By a poorly understood process, a portion of the EIN2 protein called CEND, which alone can activate ethylene responses, is cleaved and translocated from the ER to the nucleus upon exposure to ethylene. The project is to investigate the mechanism of ethylene-dependent processing of the EIN2, and to identify proteins that may mediate its nuclear translocation and/or are required for CEND function. Genetic approaches will be used to functionally assess the role of proteins that interact with the essential ethylene pathway regulator EIN2. Identification and functional ethylene signaling pathway components, along with characterization of and analysis of their interactions with the known signaling pathway components will provide new insights into the diversity of biological effects of the simple hydrocarbon, ethylene. Moreover, understanding of the functions of these proteins will enable the modification of the beneficial and/or detrimental effects of ethylene in any plant, in particular, crops with important economic or social value.
Broader impacts. The long-term goal of this research is to understand how ethylene gas promotes myriad changes in plant development and stress resistance at a very detailed, mechanistic level. The educational activities associated with this quest for basic knowledge about plant hormone signaling processes includes the training of students. The focus of the planned outreach activities centers on exposing high school students to modern plant biological research. These students will learn new ideas, concepts, and, through demonstrations, the tools and technologies of genomic and computational biology. In addition, a plan for mentoring of postdoctoral students is outlined, which involves numerous opportunities to learn the skills required for a researcher to initiate a successful scientific career. The program utilizes a variety of training tools such as ethics training, preparation of seminars, writing and reviewing of grants and papers, as well as opportunities for student mentoring.
The aim of this research is to understand how plants respond to a hormone called ethylene gas. All plants make ethylene gas and they also respond to it. There are many roles for ethylene in the life of the plant. For instance, the most well known role is in fruit ripening. However, ethylene also is important in defending plants against pathogens such as fungus. In this study, we aimed to understand how the plant "smells" ethylene and transmits this information to tell the plant to change its development or how to respond to pathogens. We focused on a particularar protein called ETHYLENE INSENSITIVE 2 of unknown function. When this protein is missing in the plant the result is an inability to sense ethylene. Ttherefore we know that EIN2 is critical for plant response to ethylene and it plays an important role in all ethylene responses. We discovered that EIN2 is located in a cell compartment called the endoplasmic reticulum and is alter by a protein modification called phosphorylation. Once the plant "smells ethylene, this modification is lost. Then, by a still unknown mechanism, the EIN2 protein is cut in half and part of the protein moves to another cell location called the nucleus where it functions to activate genes. These genes are important in the many processes that ethylene controls. Although our study used the reference plant called Arabidopsis thaliana, all plants that have been examined contain the EIN2 protein. Therefore, these findings have important implications regarding how crops resist attack by pathogens and how their fruits are ripened. Further studies are need to fully understand the role of EIN2 in controlling functions in the nucleus.
