Molecular Genetic Analysis of Ethylene Insensitive Loci in Arabidopsis

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(1) Intellectual merit of the proposed activity How plants perceive and transduce hormone signals to affect 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 detailed molecular mechanisms that underlie these biological processes, genetic, molecular, biochemical and genomic approaches are being employed using the reference plant Arabidopsis. In particular, the goal of this project is to characterize the functions of the EIN3/EIL family of master regulatory proteins of the ethylene response. EIN3 encodes a DNA-binding transcriptional activator and is a member of a small gene family of five EIN3-LIKE proteins. These proteins participate in a transcriptional regulatory cascade that controls the expression of nearly 1,000 ethylene response genes. Biochemical and genetic approaches will be employed to identify direct EIN3/EIL target genes. Genome-wide studies of gene expression and in vivo target identification will be conducted using whole genome tiling arrays. Systematic mutant screens for ethylene response phenotypes will be initiated using a whole genome "uni-mutant" collection of homozygous gene knockouts and through the use of a chemical genomics screening approach. Identification and characterization of novel ethylene signaling pathway genes 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 allow an ability to modify the beneficial and/or detrimental effects of ethylene in any plant, in particular, crops with important economic or social value.(2) Broader impacts resulting from the proposed activity.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 at four levels: high school, undergraduate, graduate and postdoctoral. One aspect of this research program on hormone signaling using the reference plant Arabidopsis is hypothesis driven but a growing part of these studies employs large-scale, data-driven or discovery-based science. In reality, both conventional hypothesis-driven, "gene-by-gene" studies as well as large-scale gathering of "part-lists" information (e.g. transcriptome, interactome, phenome) play important roles in modern biological research, in particular, to understand the interactions of these complex signaling pathways at a systems level. These students will learn these new ideas/concepts and will apply the tools and technologies of genomic and computational biology to begin to solve longstanding problems in plant science such as the regulation of growth by ethylene, extending their learning experiences beyond the traditional classroom/laboratory settings.