Uptake and Assimilation of NO2 in a Mutant of Ficus thunbergii Maxim Produced by Ion Beam Irradiation

Abstract

Atmospheric nitrogen dioxide (NO₂) is a major pollutant in the urban air. The capability of Ficus thunbergii Maxim to mitigate NO₂ was fourth-highest among 70 taxa of woody plants (Takahashi et al., Chemosphere 61: 633-639, 2005). Explants of in vitro-cultured F. thunbergii were irradiated with ion beam [¹²C⁵⁺ (220 Me V), ¹²C⁶⁺ (50 Me V) and ⁴He²⁺ (320 Me V)], and from them plants were regenerated and propagated by cutting. Plants were fumigated with ¹⁵N-labeled NO₂ at 1 ppm for 8 h, and their leaves were analyzed for total and Kjeldahl nitrogen derived from NO₂ using an EA-MS analyzer. Of 263 independent plant lines, a line showed 1.4-fold higher uptake of NO₂ than the control. This line showed 1.8-fold higher assimilation of NO₂ than the control. The present results indicate that ion beam irradiation is useful to improve the capability of Ficus thunbergii to mitigate atmospheric NO₂.