JASMONATE-INSENSITIVE1 Encodes a MYC Transcription Factor Essential to Discriminate between Different Jasmonate-Regulated Defense Responses in Arabidopsis
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Abstract
In spite of the importance of jasmonates (JAs) as plant growth and stress regulators,
the molecular components of their signaling pathway remain largely unknown. By means
of a genetic screen that exploits the cross talk between ethylene (ET) and JAs, we
describe the identification of several new loci involved in JA signaling and the characterization
and positional cloning of one of them, JASMONATE-INSENSITIVE1 (JAI1/JIN1). JIN1 encodes
AtMYC2, a nuclear-localized basic helix-loop-helix-leucine zipper transcription factor,
whose expression is rapidly upregulated by JA, in a CORONATINE INSENSITIVE1-dependent
manner. Gain-of-function experiments confirmed the relevance of AtMYC2 in the activation
of JA signaling. AtMYC2 differentially regulates the expression of two groups of JA-induced
genes. The first group includes genes involved in defense responses against pathogens
and is repressed by AtMYC2. Consistently, jin1 mutants show increased resistance to
necrotrophic pathogens. The second group, integrated by genes involved in JA-mediated
systemic responses to wounding, is activated by AtMYC2. Conversely, Ethylene-Response-Factor1
(ERF1) positively regulates the expression of the first group of genes and represses
the second. These results highlight the existence of two branches in the JA signaling
pathway, antagonistically regulated by AtMYC2 and ERF1, that are coincident with the
alternative responses activated by JA and ET to two different sets of stresses, namely
pathogen attack and wounding.
Publisher:
American Society of Plant Biologists (ASPB)
ISSN
(Print):
1040-4651
ISSN
(Electronic):
1532-298X
Publication date Created:
July
02 2004
Publication date Created:
July
2004
Publication date
(Print):
July
2004
Publication date
(Electronic):
June
18 2004
Volume: 16
Issue: 7
Pages: 1938-1950
Affiliations
[1
]Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Consejo
Superior de Investigaciones Cientificas, Campus Universidad Autónoma, 28049 Madrid,
Spain