Rola tlenku azotu w metabolizmie komórki roślinnej

Abstrakt

Summary Nitric oxide (NO) is a bioactive molecule that exerts a number of diverse activities in plants. NO in plant cells is produced by nitrate oxidase synthase (NOS) or nitrate reductase (NR). The relationship between NR activity and NO production is presented. NO coordinates and regulates the cellular function of mitochondria and reduces the total cell respiration due to strong inhibition of the cytochrome pathway. There are some reports demonstrating that NO increases the contribution of the alternative pathway to total respiration by inducing the expression of alternative oxidase (AOX). Owing to the presence of an unpaired electron the NO molecule exibits a dual mode of action. Depending on the circumstances, NO in combination with an other reactive oxygen species (ROS) may be either toxic or protective. It is able to scavenge other reactive intermediates and end chainpropagated reactions. The reaction between superoxide and NO leads to formation of peroxynitrite and it thus suggested to be a deleterious mechanism. In systems where the toxicity is due predominantly to peroxides, NO can act as a protective agent. The participation of NO in the antioxidant system in plant cells is also described.