Bight irradiation induces fragmentation of the plasmodium, a novel photomorphogenesis in the true slime mold Physarum polycephalum: Action spectra and evidence for involvement of the phytochrome

摘要

A new photomorphogenesis was found in the plasmodium of the true slime mold Physarum polycephalum: the plasmodium broke temporarily into equal-sized spherical pieces, each containing about eight nuclei, about 5 h after irradiation with light, Action spectroscopic study showed that UVA, blue and far-red lights were effective, while red light inhibited the far-red-induced fragmentation. Difference absorption spectra of both the Living plasmodium and the plasmodial homogenate after alternate irradiation,vith far-red and red light gave two extremes at 750 and 680 nm, which agreed with those for the induction and inhibition of the fragmentation, respectively. A kinetic model similar to that of phytochrome action explained quantitatively the fluence rate-response curves of the fragmentation. Our results indicate that one of the photoreceptors for the plasmodial fragmentation is a phytochrome. [References: 29]