Defense activated by 9-lipoxygenase-derived oxylipins requires specific mitochondrial proteins.
9-Lipoxygenases (9-LOXs) initiate fatty acid oxygenation, resulting in the formation of oxylipins activating plant defense against hemibiotrophic pathogenic bacteria. Previous studies using nonresponding to oxylipins (noxy), a series of Arabidopsis (Arabidopsis thaliana) mutants insensitive to the 9-LOX product 9-hydroxy-10,12,15-octadecatrienoic acid (9-HOT), have demonstrated the importance of cell wall modifications as a component of 9-LOX-induced defense. Here, we show that a majority (71%) of 41 studied noxy mutants have an added insensitivity to isoxaben, an herbicide inhibiting cellulose synthesis and altering the cell wall. The specific mutants noxy2, noxy15, and noxy38, insensitive to both 9-HOT and isoxaben, displayed enhanced susceptibility to Pseudomonas syringae DC3000 as well as reduced activation of salicylic acid-responding genes. Map-based cloning identified the mutation in noxy2 as At5g11630 encoding an uncharacterized mitochondrial protein, designated NOXY2. Moreover, noxy15 and noxy38 were mapped at the DYNAMIN RELATED PROTEIN3A and FRIENDLY MITOCHONDRIA loci, respectively. Fluorescence microscopy and molecular analyses revealed that the three noxy mutants characterized exhibit mitochondrial dysfunction and that 9-HOT added to wild-type Arabidopsis causes mitochondrial aggregation and loss of mitochondrial membrane potential. The results suggest that the defensive responses and cell wall modifications caused by 9-HOT are under mitochondrial retrograde control and that mitochondria play a fundamental role in innate immunity signaling.
Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, Cantoblanco, E-28049 Madrid, Spain.
Tamara
T
Vellosillo
Verónica
V
Aguilera
Ruth
R
Marcos
Michael
M
Bartsch
Jorge
J
Vicente
Tomas
T
Cascón
Mats
M
Hamberg
Carmen
C
Castresana
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001549:Benzamides / Q000494:pharmacology; D002473:Cell Wall / Q000378:metabolism; D060467:Disease Resistance / Q000187:drug effects / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D054884:Host-Pathogen Interactions; D008042:Linolenic Acids / Q000378:metabolism / Q000494:pharmacology; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D030821:Plants, Genetically Modified; D044224:Pseudomonas syringae / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D001549:Benzamides; D008042:Linolenic Acids; D024101:Mitochondrial Proteins; C582317:NOXY2 protein, Arabidopsis; D054883:Oxylipins; C486924:dynamin-related protein DRP3A, Arabidopsis; D049452:Green Fluorescent Proteins; C057467:isoxaben; C062142:9-hydroxy-10,12,15-octadecatrienoic acid; D008084:Lipoxygenase