JAZ4 is involved in plant defense, growth, and development in Arabidopsis

• Published in: The Plant journal : for cell and molecular biology Vol. 101; no. 2; pp. 371 - 383
• Main Authors: Oblessuc, Paula R., Obulareddy, Nisita, DeMott, Logan, Matiolli, Cleverson C., Thompson, Blaine K., Melotto, Maeli
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-01-2020
• Subjects: Amino Acids; Anthocyanins - metabolism; Arabidopsis; Arabidopsis - genetics; Arabidopsis Proteins - genetics; Arabidopsis Proteins - physiology; Arabidopsis thaliana; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors - metabolism; Biodegradation; Coronatine; Cyclopentanes; Flowering; Gene Expression Regulation, Plant; Hypocotyl - growth & development; Indenes; Isoleucine; Isoleucine - analogs & derivatives; JA response; Jas domain; Jasmonic acid; JAZ4 (At1g48500); Lycopersicon esculentum - metabolism; Mutants; Myc protein; Phenotype; Phytotoxins; Plant growth; Plant Roots - growth & development; Plants (botany); Proteasomes; Proteins; Pseudomonas syringae; Repressor Proteins - genetics; Repressor Proteins - physiology; Repressors; Signal Transduction; Signaling; Tomatoes; Trans-Activators - metabolism; Transcription factors; Arabidopsis thaliana; Jas domain; JA response; Pseudomonas syringae; coronatine; JAZ4 (At1g48500)
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14548

Summary
Jasmonate zim‐domain (JAZ) proteins comprise a family of transcriptional repressors that modulate jasmonate (JA) responses. JAZ proteins form a co‐receptor complex with the F‐box protein coronatine insensitive1 (COI1) that recognizes both jasmonoyl‐l‐isoleucine (JA‐Ile) and the bacterial‐produced phytotoxin coronatine (COR). Although several JAZ family members have been placed in this pathway, the role of JAZ4 in this model remains elusive. In this study, we observed that the jaz4‐1 mutant of Arabidopsis is hyper‐susceptible to Pseudomonas syringae pv. tomato (Pst) DC3000, while Arabidopsis lines overexpressing a JAZ4 protein lacking the Jas domain (JAZ4∆Jas) have enhanced resistance to this bacterium. Our results show that the Jas domain of JAZ4 is required for its physical interaction with COI1, MYC2 or MYC3, but not with the repressor complex adaptor protein NINJA. Furthermore, JAZ4 degradation is induced by COR in a proteasome‐ and Jas domain‐dependent manner. Phenotypic evaluations revealed that expression of JAZ4∆Jas results in early flowering and increased length of root, hypocotyl, and petiole when compared with Col‐0 and jaz4‐1 plants, although JAZ4∆Jas lines remain sensitive to MeJA‐ and COR‐induced root and hypocotyl growth inhibition. Additionally, jaz4‐1 mutant plants have increased anthocyanin accumulation and late flowering compared with Col‐0, while JAZ4∆Jas lines showed no alteration in anthocyanin production. These findings suggest that JAZ4 participates in the canonical JA signaling pathway leading to plant defense response in addition to COI1/MYC‐independent functions in plant growth and development, supporting the notion that JAZ4‐mediated signaling may have distinct branches.
Significance Statement
Some JAZ proteins are known to participate in the canonical jasmonate (JA) signaling pathway composed by the COI1 receptor and MYC transcription factors. We found that JAZ4 also plays a role in this process under biotic stress, in addition to having COI1/MYC‐independent functions in plant growth and development.