TAKEBA G. Kyoto Pref. Univ., Fac. of Living Sci., Assoc. Prof., 生活科学部, 助教授 (10046500)
HIRAI N. Kyoto Univ., Fac. of Agric., Instr., 農学部, 助手 (00165151)
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¥5,900,000 (Direct Cost : ¥5,900,000)
Fiscal Year 1990 : ¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1989 : ¥3,700,000 (Direct Cost : ¥3,700,000)
Water extracts of many plant species, in particular, Lemna paucicostata and Pharbitis nil, sensitive short-day plants, induced flowering in L. Paucicostata 151 at very low concentrations. Most of the Flower-Inducing Substance (s) (FIS), which is heat stable, was produced rapidly after homogenization of the plants. FIS was not produced during separate incubation of the supernatant and pellet obtained by centrifugation of the homogenate, and oxygen depriviation or the presence of ascorbate during incubation of the plant homogenate markedly lowered the production of FIS.
FIS was produced by incubation of the centrifuged pellet of the plant homogenate with tyrosine and this reaction did not proceed in nitrogen gas or in the presence of ascorbic acid. Catecholamines, which are oxidative metabolites of tyrosine, were also effective for the production of FIS, and Norepinephrin (NE) was the most effective. Addition of only 1 ug NE to the centrifuged pellet obtained from 100 mg fresh weight of Lemna plants produced FIS without incubation. NE was detected in the water extract of Lemna plants, and most of the NE was proved to be produced after homogenization of the plant. The mixture of NE fraction and the pellet each obtained from the same amount of Lemna plants had flower-inducing activity similar to the crude water extract. NE solution incubated with in-tact Lemna plants had high flower-inducing activity, but NE added to the water incubated with intanct Lemna plants did not. NE dissolved in KOH under some particular conditions also had flower-inducing activity. These results suggest that FIS is produced from NE. Chemical analysis of the water extract of Lemna plants also supported this possibility.
アオウキクサ水抽出液の活性フラクションは、 ^1H ^<13>C NMRにおいて解析不能な幅広いシグナルを与える。そして, ^<13> CPーMAS NMR はメラニン様スペクトルを示す。MS では EI,FAB,SIMS,FD の何れのイオン化でも有意なイオンは検出できないが、元素分析より、炭素 53%、水素 7%、窒素 8%、酸素 33% の組成比が与えられた。これらの結果などから、活性成分はカテコ-ルアミン由来のメラニン前駆体様物質であると考えられ、このことは、FIS がNE からつくられるという結論と矛盾しない。