Characterization of Citrus sinensis type 1 mitochondrial alternative oxidase and expression analysis in biotic stress

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 onl...

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Bibliographic Details
Published in:	Bioscience reports Vol. 30; no. 1; p. 59
Main Authors:	Daurelio, Lucas Damián, Checa, Susana Karina, Barrio, Jorgelina Morán, Ottado, Jorgelina, Orellano, Elena Graciela
Format:	Journal Article
Language:	English
Published:	England 01-02-2010
Subjects:	Amino Acid Sequence Anti-Infective Agents - pharmacology Base Sequence Citrus sinensis - enzymology Citrus sinensis - genetics Exons - genetics Gene Expression Regulation, Plant - genetics Host-Pathogen Interactions - genetics Host-Pathogen Interactions - immunology Immunity, Innate - genetics Immunity, Innate - immunology Mitochondrial Proteins - chemistry Mitochondrial Proteins - genetics Mitochondrial Proteins - metabolism Molecular Sequence Data Oxidoreductases - chemistry Oxidoreductases - genetics Oxidoreductases - metabolism Phylogeny Plant Diseases - genetics Plant Diseases - immunology Plant Proteins Promoter Regions, Genetic - genetics Pseudomonas syringae - metabolism Salicylic Acid - pharmacology Sequence Homology, Amino Acid Stress, Physiological - genetics Xanthomonas axonopodis - metabolism
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Summary:	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.
ISSN:	1573-4935
DOI:	10.1042/bsr20080180