Effect of atmospheric NO on plant growth and development

Plant hemoglobins are ubiquitous in all plant families. Several studies have established that class 1 non-symbiotic hemoglobin possess an extremely high affinity to oxygen and their main function consists in scavenging of nitric oxide (NO) at very low oxygen levels. We demonstrated that fumigation with up to 3 ppm NO has no negative/toxic effects on plant growth and development. In contrast, the NO-fixing capability of non-symbiotic hemoglobin proteins allows a channeling of atmospheric NO into the plant N metabolism. This pathway is probably important under conditions with limited N supply via the soil. Moreover, such a NO-fixing mechanism might displays a kind of N-recycling process by preventing loss of N and making it available for N assimilation. Analyses of metabolic fluxes in 15NO treated plants should allow us to identify the exact pathway of incorporation of N from uptaken NO into metabolites/proteins.

The NO-fixing pathway will be analysed in the model plant Arabidopsis thaliana as well as in a crop plant (barley).

Jiangli Zhang, Christian Lindermayr

Barley plants were fumigated during the whole growth phase season with different concentrations of NO gas. Growth promoting effects were observed with increasing concentrations of NO.