Title: A strong constitutive ethylene-response phenotype conferred on Arabidopsis plants containing null mutations in the ethylene receptors ETR1 and ERS1

Abstract

The ethylene receptor family of Arabidopsis consists of five members, falling into two subfamilies. Subfamily 1 is composed of ETR1 and ERS1, and subfamily 2 is composed of ETR2, ERS2, and EIN4. Although mutations have been isolated in the genes encoding all five family members, the only previous insertion allele of ERS1 (ers1-2) is a partial loss-of-function mutation based on our analysis. The purpose of this study was to determine the extent of signaling mediated by subfamily-1 ethylene receptors through isolation and characterization of null mutations. We isolated new T-DNA insertion alleles of subfamily 1 members ERS1 and ETR1 (ers1- 3 and etr1-9, respectively), both of which are null mutations based on molecular, biochemical, and genetic analyses. Single mutants show an ethylene response similar to wild type, although both mutants are slightly hypersensitive to ethylene. Double mutants of ers1-3 with etr1-9, as well as with the previously isolated etr1-7, display a constitutive ethylene-response phenotype more pronounced than that observed with any previously characterized combination of ethylene receptor mutations. Dark-grown etr1-9;ers1-3 and etr1-7;ers1-3 seedlings display a constitutive triple-response phenotype. Light-grown etr1-9;ers1-3 and etr1-7;ers1-3 plants are dwarfed, largely sterile, exhibit premature leaf senescence, and develop novel filamentous structures at the base ofmore » the flower. A reduced level of ethylene response was still uncovered in the double mutants, indicating that subfamily 2 receptors can independently contribute to signaling, with evidence suggesting that this is due to their interaction with the Raf-like kinase CTR1. Our results are consistent with the ethylene receptors acting as redundant negative regulators of ethylene signaling, but with subfamily 1 receptors playing the predominant role. Loss of a single member of subfamily 1 is largely compensated for by the activity of the other member, but loss of both subfamily members results in a strong constitutive ethylene-response phenotype. The role of subfamily 1 members is greater than previously suspected and analysis of the double mutant null for both ETR1 and ERS1 uncovers novel roles for the receptors not previously characterized.« less

Authors:

Qu, Xiang ^[1]; Hall, Brenda P. ^[2]; Gao, Zhiyong ^[2]; Schaller, G. Eric ^[2]

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+ Show Author Affiliations

1. Univ. of New Hampshire, Durham, NH (United States); California Institute of Technology (CalTech), Pasadena, CA (United States)
2. Dartmouth College, Hanover, NH (United States)

Publication Date:

Mon Jan 15 00:00:00 EST 2007

Research Org.:

Dartmouth College, Hanover, NH (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division; National Science Foundation (NSF)

OSTI Identifier:

1626510

Grant/Contract Number:  

FG02-05ER15704; MCB-0235450; MCB-0430191

Resource Type:

Accepted Manuscript

Journal Name:

BMC Plant Biology

Additional Journal Information:

Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 1471-2229

Publisher:

BioMed Central

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; Plant Sciences; Ethylene Response; Ethylene Receptor; Axillary Meristem; Hypocotyl Length; Ethylene Signal Transduction