Abstract
Plants take up nitrogen dioxide (NO2) and assimilate its nitrogen through a primary nitrate assimilation pathway. However, we found that a part of the nitrogen of NO2 is converted into compounds in plants whose nitrogen is not recoverable by the Kjeldahl method. We designated this nitrogen as unidentified nitrogen (UN). UN-bearing compounds may include nitro compounds, including nitrated protein-tyrosine. We therefore addressed nitration of protein-tyrosine in plant leaves fumigated with NO2.
Tobacco plants (Nicotiana tabacum cv. Xanthi) were fumigated with 4 ppm NO2 for 8 h, and from their leaves protein extracts were prepared. The proteins in the extracts were separated using SDS PAGE and 2-D PAGE and then analyzed immunologically. Spots that react with the antibody were detected, and mass spectroscopic analyses identified them as pathogenesis-related proteins. This result indicates that nitration of protein occurs in response to fumigation of plants with NO2.
