The plant hormone, ethylene, regulates a wide range of physiological and developmental processes in higher plants. While a significant amount of progress has recently been made in the elucidation of the ethylene biosynthetic pathway and in the molecular bases for a number of ethylene regulated processes, virtually nothing is known about the receptor and associated signal transduction pathways in plants. The goal of this proposal is the molecular cloning and characterization of the ETR locus in Arabidopsis thalina. Mutations in the ETR locus have been isolated which cause insensitivity to a number of ethylene responses in the plant. Physiological evidence indicates that the mutations directly effect the ethylene receptor. From a chromosome walk, an 18 kb region of cloned genomic DNA has been obtained which appears to carry the ETR gene. The investigators intend to identify the specify sequences in this region that represent the ETR gene and to obtain full length cDNA clones of the mutant and wild type genes. The cDNA clones will also be used to manipulate the level of expression of the wild type and mutant gene products in transgenic Arabidopsis and in a number of other plant species. Engineered mutations in the gene will allow an exploration of the dominant nature of the etr phenotype.
