Article: article from journal or magazin.
Role of NINJA in root jasmonate signaling.
Proceedings of the National Academy of Sciences of the United States of America
Wound responses in plants have to be coordinated between organs so that locally reduced growth in a wounded tissue is balanced by appropriate growth elsewhere in the body. We used a JASMONATE ZIM DOMAIN 10 (JAZ10) reporter to screen for mutants affected in the organ-specific activation of jasmonate (JA) signaling in Arabidopsis thaliana seedlings. Wounding one cotyledon activated the reporter in both aerial and root tissues, and this was either disrupted or restricted to certain organs in mutant alleles of core components of the JA pathway including COI1, OPR3, and JAR1. In contrast, three other mutants showed constitutive activation of the reporter in the roots and hypocotyls of unwounded seedlings. All three lines harbored mutations in Novel Interactor of JAZ (NINJA), which encodes part of a repressor complex that negatively regulates JA signaling. These ninja mutants displayed shorter roots mimicking JA-mediated growth inhibition, and this was due to reduced cell elongation. Remarkably, this phenotype and the constitutive JAZ10 expression were still observed in backgrounds lacking the ability to synthesize JA or the key transcriptional activator MYC2. Therefore, JA-like responses can be recapitulated in specific tissues without changing a plant's ability to make or perceive JA, and MYC2 either has no role or is not the only derepressed transcription factor in ninja mutants. Our results show that the role of NINJA in the root is to repress JA signaling and allow normal cell elongation. Furthermore, the regulation of the JA pathway differs between roots and aerial tissues at all levels, from JA biosynthesis to transcriptional activation.
Analysis of Variance, Arabidopsis/growth & development, Arabidopsis/metabolism, Arabidopsis Proteins/genetics, Arabidopsis Proteins/metabolism, DNA Primers, Flowers/genetics, Flowers/growth & development, Gene Components, Gene Expression Profiling, High-Throughput Nucleotide Sequencing, Nuclear Proteins/genetics, Nuclear Proteins/metabolism, Plant Roots/genetics, Plant Roots/growth & development, Real-Time Polymerase Chain Reaction, Repressor Proteins/genetics, Repressor Proteins/metabolism, Seedling/growth & development, Seedling/metabolism, Signal Transduction/physiology
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