Present address: Faculty of Horticulture, Chiba University, Matsubo 648, Matsubo, Chiba 271-8510, Japan.
Nitric oxide emission from tobacco leaves and cell suspensions: rate limiting factors and evidence for the involvement of mitochondrial electron transport
Article first published online: 25 JAN 2005
The Plant Journal
Volume 41, Issue 5, pages 732–743, March 2005
How to Cite
Planchet, E., Jagadis Gupta, K., Sonoda, M. and Kaiser, W. M. (2005), Nitric oxide emission from tobacco leaves and cell suspensions: rate limiting factors and evidence for the involvement of mitochondrial electron transport. The Plant Journal, 41: 732–743. doi: 10.1111/j.1365-313X.2005.02335.x
- Issue published online: 2 FEB 2005
- Article first published online: 25 JAN 2005
- Received 12 October 2004; revised 1 December 2004; accepted 13 December 2004.
- MoCo enzymes;
- Nicotiana tabacum;
- nitrate reductase;
- nitric oxide;
- NO emission
Quantitative data on nitric oxide (NO) production by plants, and knowledge of participating reactions and rate limiting factors are still rare. We quantified NO emission from tobacco (Nicotiana tabacum) wild-type leaves, from nitrate reductase (NR)- or nitrite reductase (NiR)-deficient leaves, from WT- or from NR-deficient cell suspensions and from mitochondria purified from leaves or cells, by following NO emission through chemiluminescence detection. In all systems, NO emission was exclusively due to the reduction of nitrite to NO, and the nitrite concentration was an important rate limiting factor. Using inhibitors and purified mitochondria, mitochondrial electron transport was identified as a major source for reduction of nitrite to NO, in addition to NR. NiR and xanthine dehydrogenase appeared to be not involved. At equal respiratory activity, mitochondria from suspension cells had a much higher capacity to produce NO than leaf mitochondria. NO emission in vivo by NiR-mutant leaves (which was not nitrite limited) was proportional to photosynthesis (high in light +CO2, low in light −CO2, or in the dark). With most systems including mitochondrial preparations, NO emission was low in air (and darkness for leaves), but high under anoxia (nitrogen). In contrast, NO emission by purified NR was not much different in air and nitrogen. The low aerobic NO emission of darkened leaves and cell suspensions was not due to low cytosolic NADH, and appeared only partly affected by oxygen-dependent NO scavenging. The relative contribution of NR and mitochondria to nitrite-dependent NO production is estimated.