The Arabidopsis Malectin-Like/LRR-RLK IOS1 Is Critical for BAK1-Dependent and BAK1-Independent Pattern-Triggered Immunity.

Abstract

Plasma membrane-localized pattern recognition receptors (PRRs) such as FLAGELLIN SENSING2 (FLS2), EF-TU RECEPTOR (EFR), and CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) recognize microbe-associated molecular patterns (MAMPs) to activate pattern-triggered immunity (PTI). A reverse genetics approach on genes responsive to the priming agent β-aminobutyric acid (BABA) revealed IMPAIRED OOMYCETE SUSCEPTIBILITY1 (IOS1) as a critical PTI player. Arabidopsis thaliana ios1 mutants were hypersusceptible to Pseudomonas syringae bacteria. Accordingly, ios1 mutants showed defective PTI responses, notably delayed upregulation of the PTI marker gene FLG22-INDUCED RECEPTOR-LIKE KINASE1, reduced callose deposition, and mitogen-activated protein kinase activation upon MAMP treatment. Moreover, Arabidopsis lines overexpressing IOS1 were more resistant to bacteria and showed a primed PTI response. In vitro pull-down, bimolecular fluorescence complementation, coimmunoprecipitation, and mass spectrometry analyses supported the existence of complexes between the membrane-localized IOS1 and BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1)-dependent PRRs FLS2 and EFR, as well as with the BAK1-independent PRR CERK1. IOS1 also associated with BAK1 in a ligand-independent manner and positively regulated FLS2-BAK1 complex formation upon MAMP treatment. In addition, IOS1 was critical for chitin-mediated PTI. Finally, ios1 mutants were defective in BABA-induced resistance and priming. This work reveals IOS1 as a novel regulatory protein of FLS2-, EFR-, and CERK1-mediated signaling pathways that primes PTI activation.

• Authors: Yu-Hung Yeh, Dario Panzeri, Yasuhiro Kadota, Yi-Chun Huang, Pin-Yao Huang, Chia-Nan Tao, Milena Roux, Hsiao-Chiao Chien, Tzu-Chuan Chin, Po-Wei Chu, Cyril Zipfel, Laurent Zimmerli
• Journal: The Plant cell (Plant Cell) Vol. 28 Issue 7 Pg. 1701-21 (07 2016) ISSN: 1532-298X [Electronic] England
• PMID: 27317676 (Publication Type: Journal Article)
• Copyright: © 2016 American Society of Plant Biologists. All rights reserved.

Chemical References

• Aminobutyrates
• Arabidopsis Proteins
• 3-aminobutyric acid
• At1g51800 protein, Arabidopsis
• Protein Kinases
• BAK1 protein, Arabidopsis
• FLS2 protein, Arabidopsis
• Protein Serine-Threonine Kinases
• Mitogen-Activated Protein Kinases

Topics

• Aminobutyrates (metabolism)
• Arabidopsis (genetics, metabolism, microbiology)
• Arabidopsis Proteins (genetics, metabolism)
• Mitogen-Activated Protein Kinases (genetics, metabolism)
• Plant Immunity (genetics, physiology)
• Protein Kinases (genetics, metabolism)
• Protein Serine-Threonine Kinases (genetics, metabolism)
• Pseudomonas syringae (pathogenicity)