カフェー酸の生長阻害作用, およびこれを軽減するMn++の作用について

Abstract

1) The elongation of Avena coleoptile sections was inhibited by caffeic acid, at 5×10-4M, and this inhibition was partly alleviated by Mn++, at a concentration of 10-3M. This alleviation, however, was not observed when the test solution contained 10-4M p-nitrophenol. At this concentration, p-nitrophenol showed little inhibition on the IAA-induced elongation of Avena coleoptile sections and no effect on the growth inhibiting activity of caffeic acid.2) During the incubation with Avena coleoptile sections, some portion of caffeic acid disappeared from the test solution and a substance ('spot 2' in Table 2) appeared in the solution. This substance also inhibited the growth of Avena coleoptile and the color reaction of IAA with Salkowski's reagent. But in the presence of Mn++ (10-3M), though the formation of 'spot 2' was scarcely observed, caffeic acid decreased in its concentration. Addition of p-nitrophenol, at 10-4M, to the test solution inhibited both the disappearance of caffeic acid and the formation of 'spot 2'.3) The inhibitor ('spot 2') that appeared in the test solution might be an o-dihydroxyphenol having a carbonyl group, and was considered as a product formed from caffeic acid.4) Discussion was made on the reason why Mn++ prevents the inhibition caused by caffeic acid.