Abstract
As reported previously, about one-third of inorganic nitrogen, such as N of nitrogen dioxide and nitrate, taken up into plant body is converted to Kjeldahl-unrecoverable, hitherto unknown organic nitrogen (UN). UN bearing compounds include those in which a nitrogen atom is linked to an oxygen atom or atoms, e.g. nitro, nitroso, and oxime groups, or to a second nitrogen atom, e.g. azo compounds and hydrazines (Morikawa et al., 2004). There is an alternative pathway in the N metabolism to form the UN-bearing compounds. Some UN-bearing compounds, if not all, may be involved as a signal molecule in the plant vitalization effect of atmospheric nitrogen oxides (Takahashi et al., 2005). This communication summarizes what have been done and what are to be done in the study on the novel aspect of N metabolism.
Morikawa, H. et al. Planta.219: 14-22 (2004).
Takahashi, M. et al. New Phytol. 168: 149-154 (2005).
