Molecular Genetic Analysis of Ethylene Insensitive Loci in Arabidopsis

The Salk Institute For Biological Studies, La Jolla CA

Investigators

Abstract

How plants perceive and transduce hormone signals is a fundamental question in biology that also has important practical applications. The response to ethylene gas serves as a paradigm for understanding 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). Understanding of these various roles of ethylene are being addressed using genetic, molecular and biochemical approaches in Arabidopsis. In particular, the goal of this project is to characterize the functions of the EIN3/EIL family of plant specific DNA-binding proteins in ethylene-mediated transcriptional regulation. EIN3 encodes a DNA-binding transcriptional activator protein and is a member of a small gene family of EIN3-LIKE (EIL1, EIL2, EIL3, EIL4, EIL5) proteins. Along with another transcription activator called ERF1, the EIN3/EIL proteins participate in a little understood transcriptional regulatory cascade. This project will investigate how the activities of the EIN3/EIL proteins are modulated by ethylene and also explore the roles of these proteins in mediating ethylene signaling to the various downstream responses. In particular, the possibility of posttranslational modification(s), changes in protein stability or alterations in the subcellular localization of EIN3/EIL proteins in response to ethylene will be examined. In addition, biochemical and genetic approaches will be employed to identify EIN3/EIL interacting proteins. Analysis of individual EIL1,EIL2, EIL3, EIL4, and EIL5 loss-of-function mutants, various multiple mutant combinations and ectopic expression of these genes will provide significant new insight into the possible functions of these genes in downstream responses to ethylene. In addition, genome-wide studies of EIN3/EIL gene expression and in vivo target identification will be conducted using custom gene expression and whole genome tiling arrays, respectively. Identification and characterization of the EIN3/EIL ethylene signaling pathway genes and analysis of their interactions with other signaling pathway components will provide new insights into tremendous diversity of biological affects of the simple hydrocarbon, ethylene. Moreover, understanding of the functions of these proteins will allow the ability to modify the beneficial and/or detrimental effects of ethylene in any plant, in particular, crops with important economic or social value.