The Production of N-labeled nitrogen gas tracer and the imaging of nitrogen fixation in soybean nodules

N標識窒素ガストレーサーの製造及びダイズ根粒における窒素固定イメージング

石井 里美; 鈴井 伸郎; 伊藤 小百合; 石岡 典子; 河地 有木; 松橋 信平; 大竹 憲邦*; 大山 卓爾*; 藤巻 秀

Ishii, Satomi; Suzui, Nobuo; Ito, Sayuri; Ishioka, Noriko; Kawachi, Naoki; Matsuhashi, Shimpei; Otake, Norikuni*; Oyama, Takuji*; Fujimaki, Shu

The nodule is a symbiotic organ of leguminous plants with rhizobium. Soybean plants utilize nitrogen (N) fixed by nodules from atmospheric N. Until now, N, a stable isotope, has long been used for studies of N fixation. However, because this method is invasive, it has been difficult to analyze an instant response to an environmental (ex. temperature, light) changes. The purpose of our study is to image the N fixation and analyze the kinetics quantitatively and noninvasively by using nitrogen gas labeled with N (half life: 10 min), a positron emitting isotope, and PETIS (positron-emitting tracer imaging system). Previously, we succeeded in producing N-labeled nitrogen gas However, it was required to purify the gas because it was likely to contain physiologically active N-labeled impurities. In this paper, we report development of a new method of production of pure N and the imaging of nitrogen fixation.