The NgAOX1a gene cloned from Nicotiana glutinosa is implicated in the response to abiotic and biotic stresses.
A novel gene, named NgAOX1a, was isolated from Nicotiana glutinosa by RT-PCR (reverse transcription-PCR). The full-length cDNA of NgAOX1a was 1448 bp, including a 1062-bp ORF (open reading frame), a 124 bp 5' UTR (untranslated region) and a 262 bp 3' UTR. The ORF encodes a 353-amino-acid protein which contains two conserved cysteine residues, four iron-binding motifs, five alpha-helix regions and six conserved histidine residues. The phylogenetic tree showed that NgAOX1a belongs to the AOX1 (alternative oxidase 1)-type group. Alignment analysis showed that NgAOX1a shares a high similarity with other known AOXs. Four exons and three introns were detected in the genomic DNA sequence, and Southern-blotting analysis suggested that NgAOX1a is a single-copy gene. A series of putative cis-acting elements were examined in the 5'-flanking region of NgAOX1a. Northern-blotting analysis showed that the transcript levels of NgAOX1a can be markedly accumulated when tobacco seedlings are treated with various abiotic stimuli, such as exogenous signalling molecules for plant defence response, salicylic acid and H(2)O(2), and the exogenous TCA (tricarboxylic acid) cycle metabolite citrate. However, it could be suppressed by abiotic stress, such as CoCl(2), an inhibitor of ethylene, which indicates that the expression of NgAOX1a may be regulated by ethylene. In addition, NgAOX1a can also be strongly induced by three viral pathogens, tobacco mosaic virus, potato virus X and potato virus Y. These results indicate that NgAOX1a may be involved in multi-signal transduction pathways and may play an important role in defence response.
Wang
Jian
J
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, People's Republic of China.
Wang
Xia
X
Liu
Cheng
C
Zhang
Jiedao
J
Zhu
Changxiang
C
Guo
Xingqi
X
D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D020816:Amino Acid Motifs / Q000235:genetics; D001665:Binding Sites / Q000235:genetics; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007501:Iron / Q000378:metabolism; D024101:Mitochondrial Proteins; D016366:Open Reading Frames / Q000235:genetics; D010088:Oxidoreductases / Q000096:biosynthesis* / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D036226:Seedlings / Q000201:enzymology / Q000821:virology; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013312:Stress, Physiological; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000378:metabolism; D000099188:Alternative Oxidase
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D007501:Iron; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D000099188:Alternative Oxidase