Aspartate oxidase plays an important role in Arabidopsis stomatal immunity

Macho, Alberto P, Boutrot, Freddy, Rathjen, John P and Zipfel, Cyril (2012) Aspartate oxidase plays an important role in Arabidopsis stomatal immunity. Plant Physiology, 159 (4). pp. 1845-1856. ISSN 0032-0889

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Perception of pathogen-associated molecular patterns (PAMPs), such as bacterial flagellin (or the peptide flg22), by surface-localized receptors activates defense responses and subsequent immunity. In a previous forward-genetic screen aimed at the identification of Arabidopsis (Arabidopsis thaliana) flagellin-insensitive (fin) mutants, we isolated fin4, which is severely affected in flg22-triggered reactive oxygen species (ROS) bursts. Here, we report that FIN4 encodes the chloroplastic enzyme ASPARTATE OXIDASE (AO), which catalyzes the first irreversible step in the de novo biosynthesis of NAD. Genetic studies on the role of NAD have been hindered so far by the lethality of null mutants in NAD biosynthetic enzymes. Using newly identified knockdown fin alleles, we found that AO is required for the ROS burst mediated by the NADPH oxidase RBOHD triggered by the perception of several unrelated PAMPs. AO is also required for RBOHD-dependent stomatal closure. However, full AO activity is not required for flg22-induced responses that are RBOHD independent. Interestingly, although the fin4 mutation dramatically affects RBOHD function, it does not affect functions carried out by other members of the RBOH family, such as RBOHC and RBOHF. Finally, we determined that AO is required for stomatal immunity against the bacterium Pseudomonas syringae. Altogether, our work reveals a novel specific requirement for AO activity in PAMP-triggered RBOHD-dependent ROS burst and stomatal immunity. In addition, the availability of viable mutants for the chloroplastic enzyme AO will enable future detailed studies on the role of NAD metabolism in different cellular processes, including immunity, in Arabidopsis.

Item Type: Article
Uncontrolled Keywords: abscisic acid,amino acid oxidoreductases,arabidopsis,arabidopsis proteins,chitin,flagellin,genes, plant,mutagenesis, insertional,mutation,nadph oxidase,niacin,plant immunity,plant roots,plant stomata,pseudomonas syringae,reactive oxygen species,receptors, pattern recognition
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Science > The Sainsbury Laboratory
UEA Research Groups: Faculty of Science > Research Groups > Plant Sciences
Depositing User: Pure Connector
Date Deposited: 04 Jul 2014 12:44
Last Modified: 24 Oct 2022 06:25
DOI: 10.1104/pp.112.199810

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