Effect of nitrate supply and mycorrhizal inoculation on characteristics of tobacco root plasma membrane vesicles.
Plant plasma membrane (pm) vesicles from mycorrhizal tobacco (Nicotiana tabacum cv. Samsun) roots were isolated with negligible fungal contamination by the aqueous two-phase partitioning technique as proven by fatty acid analysis. Palmitvaccenic acid became apparent as an appropriate indicator for fungal membranes in root pm preparations. The pm vesicles had a low specific activity of the vanadate-sensitive ATPase and probably originated from non-infected root cells. In a phosphate-limited tobacco culture system, root colonisation by the vesicular arbuscular mycorrhizal fungus, Glomus mosseae, is inhibited by external nitrate in a dose-dependent way. However, detrimental high concentrations of 25 mM nitrate lead to the highest colonisation rate observed, indicating that the defence system of the plant is impaired. Nitric oxide formation by the pm-bound nitrite:NO reductase increased in parallel with external nitrate supply in mycorrhizal roots in comparison to the control plants, but decreased under excess nitrate. Mycorrhizal pm vesicles had roughly a twofold higher specific activity as the non-infected control plants when supplied with 10-15 mM nitrate.
Moche
Martin
M
Institute of Botany and Landscape Ecology, Greifswald University, Grimmer Str. 88, 17487 Greifswald, Germany.
Stremlau
Stefanie
S
Hecht
Lars
L
Göbel
Cornelia
C
Feussner
Ivo
I
Stöhr
Christine
C
D018533:Biomass; D002462:Cell Membrane / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D055137:Glomeromycota / Q000187:drug effects / Q000502:physiology*; D038821:Mycorrhizae / Q000187:drug effects / Q000502:physiology*; D009566:Nitrates / Q000378:metabolism / Q000494:pharmacology*; D009572:Nitrite Reductases / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014026:Nicotiana / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology*
D005227:Fatty Acids; D009566:Nitrates; D010088:Oxidoreductases; D009572:Nitrite Reductases; C034747:nitric-oxide reductase