Arabidopsis SIZ1 positively regulates alternative respiratory bypass pathways.
Plant mitochondria possess alternative respiratory pathways mediated by the type II NAD(P)H dehydrogenases and alternative oxidases. Here, E3 SUMO ligase was shown to regulate alternative respiratory pathways and to participate in the maintenance of carbon and nitrogen balance in Arabidopsis. The transcript abundance of the type II NAD(P)H dehydrogenases NDA2 and NDB2 and alternative oxidases AOX1a and AOX1d genes was low in siz1-2 mutants compared to that in wild-type. The addition of nitrate or ammonium resulted in a decrease or an increase in the expression of the same gene families, respectively, in both wild-type and siz1-2 mutants. The amount of free sugar (glucose, fructose and sucrose) was lower in siz1-2 mutants than that in wild-type. These results indicate that low nitrate reductase activity due to the AtSIZ1 mutation is correlated with an overall decrease in alternative respiration and with a low carbohydrate content to maintain the carbon to nitrogen ratio in siz1-2 mutants.
Department of Plant Science, Research Institute for Agriculture and Life Sciences, and Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea.
Bong Soo
BS
Park
Sung-Il
SI
Kim
Jong Tae
JT
Song
Hak Soo
HS
Seo
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002244:Carbon; D018506:Gene Expression Regulation, Plant; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009252:NADPH Dehydrogenase / Q000235:genetics / Q000378:metabolism; D050901:Nitrate Reductase / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D000099188:Alternative Oxidase
D029681:Arabidopsis Proteins; D002244:Carbon; D008025:Ligases; D024101:Mitochondrial Proteins; D009252:NADPH Dehydrogenase; D050901:Nitrate Reductase; D009584:Nitrogen; D010088:Oxidoreductases; D010940:Plant Proteins; D044767:Ubiquitin-Protein Ligases; D000099188:Alternative Oxidase; C502552:SIZ1 protein, Arabidopsis