Molecular Genetic Analysis of Ethylene Insensitive Loci in Arabidopsis

The Salk Institute For Biological Studies, La Jolla CA

Investigators

Abstract

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.