Poster: Late and Moved Abstracts

Abs # 946: REVERSION-TO-ETHYLENE-SENSITIVITY1 (RTE1) encodes a novel regulator of the ETR1 ethylene receptor

Presenter:	Resnick, Josephine S., stockton@wam.umd.edu
Authors	Resnick, Josephine S. (A)   Wen, Chi-Kuang  (B)   Shockey, Jason A (A)   Chang, C  (A)
Affiliations:	(A): University Of Maryland (B): National Laboratory of Plant Molecular Genetics, China

Ethylene is a gaseous plant hormone that has profound effects on plant growth and development. Genetic analysis has been central in the elucidation of the ethylene-signaling pathway, made possible through the isolation of both insensitive and constitutive response mutants. Ethylene-insensitive mutants fail to exhibit the classic triple response displayed by Arabidopsis seedlings grown in the dark in the presence of ethylene. The etr1-2 ethylene receptor mutant displays weak ethylene insensitivity. We utilized etr1-2 in a screen for new components in the ethylene-signaling pathway and identified the REVERSION-TO-ETHYLENE–SENSITIVITY-1 (RTE1) locus through the isolation of two mutant alleles. Both alleles suppress the etr1-2 ethylene-insensitive phenotype, and genetic analysis suggests that loss-of-function mutations in RTE1 specifically reduce the function of wild-type ETR1 and the mutant ETR1-2 receptor. Interestingly, rte1 mutations are unable to suppress strong ethylene-insensitive mutations, and do not appear to affect the four ethylene receptors other than ETR1. We cloned RTE1 by positional cloning and found it to encode a novel integral membrane protein with homologs in animals and in other plants. Animals have a single RTE1 gene, wheras plants have two copies. Sequence analysis reveals two regions of conserved cysteine and histidine residues reminiscent of metal binding proteins; the rte1-1 allele codes for an amino acid substitution at one of these cysteine residues. One hypothesis is that RTE1 may be important in delivering copper ions to ETR1, which requires a copper cofactor in order to bind ethylene.