MUTANTS OF FICUS PUMILA PRODUCED BY ION BEAM IRRADIATION WITH AN IMPROVED ABILITY TO UPTAKE AND ASSIMILATE ATMOSPHERIC NITROGEN DIOXIDE

Production of novel mutants with a high ability to mitigate pollutants is important for phytoremediation. We investigated the use of ion beam irradiation to produce mutants of Ficus pumila L. with an improved ability to mitigate atmospheric nitrogen dioxide (NO2). More than 25,000 shoot explants were irradiated with an ion beam (C-12(5+), C-12(6+), or He-4(2+)), from which 263 independent plant lines were obtained. The plants were analyzed for NO2 uptake by fumigation with 1 ppm N-15-labeled NO2 for 8 h in light, followed by mass spectrometric analysis. The mean NO2 uptake values of each of the 263 lines differed over a 110-fold range. Propagation was attempted using cuttings from 44 lines showing the greatest NO2 uptake; in total, 15 lines were propagated. Two of the 15 lines showed a mean NO2 uptake 1.7- to 1.8-fold greater than that of the wild-type. This increase in NO2 uptake was heritable in both lines; their progenies showed a significantly greater ability to take up and assimilate NO2 than did the wild-type. RAPD analysis demonstrated DNA variation between the progeny plants and the wild type, suggesting that the progeny were true mutants. These mutants of F. pumila may prove useful in mitigating atmospheric NO2.