ヘアリーベッチにおけるシアナミドの生合成部位

Cyanamide (NH_2CN) has been isolated from hairy vetch Vicia villosa subsp. varia as a natural product for the first time. We have already clarified that the cyanamide content in hairy vetch seedlings cultivated in the growth chamber reaches its maximum at 3-4 week. The present study aims at elucidating the organ in which cyanamide is biosynthesized. The cyanamide contents in the leaves, the stems, and the roots of 4-week-old seedlings were 629 ± 209, 256 ± 134, and < 20 μg/gFW (average ± SD), respectively. This suggests that cyanamide is biosynthesized in the aerial parts (the leaves plus the stems). To investigate the cyanamide-biosynthesizing organ, we compared the ^^<15>N incorporation into cyanamide in the whole aerial parts to that in the apical portion including the younger leaves. The ^^<15>N isotope abundance ratio in the isolated cyanamide was 3.99 ± 0.61% (average ± SE) when the whole aerial parts was incubated with ^^<15>N-labeled nitrogen sources, which was significantly higher than that of control (0.28 ± 0.03%). In contrast, the cyanamide isolated from the apical portion was not ^^<15>N-labeled on the same condition. These results imply that cyanamide is biosynthesized in the mature leaves.