Nitrite as the major source of nitric oxide production by Arabidopsis thaliana in response to Pseudomonas syringae.
The origin of nitric oxide (*NO) in plants is unclear and an *NO synthase (NOS)-like enzyme and nitrate reductase (NR) are claimed as potential sources. Here we used wild-type and NR-defective double mutant plants to investigate *NO production in Arabidopsis thaliana in response to Pseudomonas syringae pv maculicola. NOS activity increased substantially in leaves inoculated with P. syringae. However, electron paramagnetic resonance experiments showed a much higher *NO formation that was dependent on nitrite and mitochondrial electron transport rather than on arginine or nitrate. Overall, these results indicate that NOS, NR and a mitochondrial-dependent nitrite-reducing activity cooperate to produce *NO during A. thaliana-P. syringae interaction.
Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, CP 6109, Campinas, SP 13083-970, Brazil.
Luzia V
LV
Modolo
Ohara
O
Augusto
Irene M G
IM
Almeida
Jose R
JR
Magalhaes
Ione
I
Salgado
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology*; D004578:Electron Spin Resonance Spectroscopy; D009154:Mutation; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000382:microbiology; D044224:Pseudomonas syringae / Q000502:physiology*
D009573:Nitrites; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D009565:Nitrate Reductases; D050901:Nitrate Reductase