title: Characterization of Citrus sinensis type 1 mitochondrial alternative oxidase and expression analysis in biotic stress.
abstract: The higher plant mitochondrial electron transport chain contains an alternative pathway that ends with the AOX (alternative oxidase). The AOX proteins are encoded by a small gene family composed of two discrete gene subfamilies. Aox1 is present in both monocot and eudicot plants, whereas Aox2 is only present in eudicot plants. We isolated a genomic clone from Citrus sinensis containing the Aox1a gene. The orange Aox1a consists of four exons interrupted by three introns and its promoter harbours diverse putative stress-specific regulatory motifs including pathogen response elements. The role of the Aox1a gene was evaluated during the compatible interaction between C. sinensis and Xanthomonas axonopodis pv. citri and no induction of the Aox1a at the transcriptional level was observed. On the other hand, Aox1a was studied in orange plants during non-host interactions with Pseudomonas syringae pv. tomato and Xanthomonas campestris pv. vesicatoria, which result in hypersensitive response. Both phytopathogens produced a strong induction of Aox1a, reaching a maximum at 8 h post-infiltration. Exogenous application of salicylic acid produced a slight increase in the steady-state level of Aox1a, whereas the application of fungi elicitors showed the highest induction. These results suggest that AOX1a plays a role during biotic stress in non-host plant pathogen interaction.
authors.affiliation: Molecular Biology Division, IBR (Instituto de Biologia Molecular y Celular de Rosario), CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), Universidad Nacional de Rosario, Suipacha 531, (S2002LRK) Rosario, Argentina.
authors.forename: Lucas Damián
authors.initials: LD
authors.lastname: Daurelio
authors.forename: Susana Karina
authors.initials: SK
authors.lastname: Checa
authors.forename: Jorgelina Morán
authors.initials: JM
authors.lastname: Barrio
authors.forename: Jorgelina
authors.initials: J
authors.lastname: Ottado
authors.forename: Elena Graciela
authors.initials: EG
authors.lastname: Orellano
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology; D001483:Base Sequence; D032084:Citrus sinensis / Q000201:enzymology* / Q000235:genetics*; D005091:Exons / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000276:immunology; D007113:Immunity, Innate / Q000235:genetics / Q000276:immunology; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology; D010940:Plant Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics; D044224:Pseudomonas syringae / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological / Q000235:genetics*; D053532:Xanthomonas axonopodis / Q000378:metabolism; D000099188:Alternative Oxidase
chemical_list: D000890:Anti-Infective Agents; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D020156:Salicylic Acid; D000099188:Alternative Oxidase