title: The combined nitrate reductase and nitrite-dependent route of NO synthesis in potato immunity to Phytophthora infestans.
abstract: In contrast to the in-depth knowledge concerning nitric oxide (NO) function, our understanding of NO synthesis in plants is still very limited. In view of the above, this paper provides a step by step presentation of the reductive pathway for endogenous NO generation involving nitrate reductase (NR) activity and nitrite implication in potato defense to Phytophthora infestans. A biphasic character of NO emission, peaking mainly at 3 and then at 24 hpi, was detected during the hypersensitive response (HR). In avr P. infestans potato leaves enhanced NR gene and protein expression was tuned with the depletion of nitrate contents and the increase in nitrite supply at 3 hpi. In the same time period a temporary down-regulation of nitrite reductase (NiR) and activity was found. The study for the link between NO signaling and HR revealed an up-regulation of used markers of effective defense, i.e. Nonexpressor of PR genes (NPR1), thioredoxins (Thx) and PR1, at early time-points (1-3 hpi) upon inoculation. In contrast to the resistant response, in the susceptible one a late overexpression (24-48 hpi) of NPR1 and PR1 mRNA levels was observed. Presented data confirmed the importance of nitrite processed by NR in NO generation in inoculated potato leaves. However, based on the pharmacological approach the potential formation of NO from nitrite bypassing the NR activity during HR response to P. infestans has also been discussed.
authors: Department of Plant Physiology, Poznan University of Life Sciences, Wolynska 35, 60-637, Poznan, Poland. Electronic address: florysza@up.poznan.pl.
authors: Jolanta
authors: J
authors: Floryszak-Wieczorek
authors: Department of Plant Ecophysiology, Adam Mickiewicz University, Umultowska 89, 61-614, Poznan, Poland.
authors: Magdalena
authors: M
authors: Arasimowicz-Jelonek
authors: Department of Plant Ecophysiology, Adam Mickiewicz University, Umultowska 89, 61-614, Poznan, Poland.
authors: Karolina
authors: K
authors: Izbiańska
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D050901:Nitrate Reductase / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000378:metabolism; D009572:Nitrite Reductases / Q000235:genetics / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D055750:Phytophthora infestans / Q000472:pathogenicity*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011198:Solanum tuberosum / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000382:microbiology*; D017973:Tungsten Compounds / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D009573:Nitrites; D010940:Plant Proteins; D017973:Tungsten Compounds; D009569:Nitric Oxide; D009572:Nitrite Reductases; D050901:Nitrate Reductase; C045951:tungstate
keywords: Nitrate and nitrite; Nitrate reductase; Nitric oxide; Nitrite reductase; Non-enzymatic NO formation; Phytophthora infestans, potato