禾穀類の発芽ならびに幼作物のオーキシン代謝に関する研究 : 第3報小麦幼植物におけるインドール酢酸破壊機構

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The mechanism of IAA-destroying system in the wheat seedling is discussed in this paper. The IAA-oxidase activity in the crude homogenate of dark-grown wheat seedlings is masked by the existence of the IAA-oxidase inhibitors in the homogenate, but the addition of H_2O_2 to the homogenate removes this masking and the high IAA-oxidase activity becomes visible. Then, the ferulic acid, one of the IAA-oxidase inhibitors, H_2O_2 and the dialysed enzyme solution from whet coleoptile were mixed and incubated for detecting the changes in UV-absorption spectrum of the mixture. As a result, it was observed that the ferulic acid in the mixture was oxidized by the H_2O_2-peroxidase system. The masking of IAA-oxidase activity in the crude homogenate is also removed by the addition of riboflavin (FR) or flavin mononucleotide (FMN) and light instead of H_2O_2, but the enhancement of IAA-destroying action by FR (FMN) and light is observed without enzyme preparation in the mixture. This sesult suggests that it is the non-enzymatic destruction of IAA. It was also observed that this non-enzymatic destruction of IAA by FR (FMN) and light is inhibited by IAA-oxidase inhibitors, phenolics, contained in wheat seedlings. From the above-mentioned results, the authors have supposed the scheme of IAA-destroying system in wheat seedling as shown in Fig. 5.
1969-03-10