Ammonium Ions Control Gametic Differentiation and Dedifferentiation in Chlamydomonas reinhardtii : GROWTH AND DEVELOPMENT : ENVIRONMENTAL AND STRESS RESPONSES

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Effects of various nitrogen-containing compounds on gametic differentiation and dedifferentiation in Chlamydomonas reinhardtii were studied. Vegetative cells grown either non-synchronously or synchronously differentiated to gametes within 8 h in NH_4Cl-free medium. Addition of arginine did not interfere with gametic differentiation although arginine was utilized by the gametes for the progression of the cell cycle. Fully differentiated gametes dedifferentiated rapidly to vegetative cells upon feeding with NH^+_4 ions but not with arginine. Other utilizable sources of organic nitrogen, such as glutamine, ornithine, and argininosuccinate, were also unable to induce the dedifferentiation of gametes. When gametes were incubated with _<DL>-methionine-_<DL>-sulfoximine (MSX) and NH^+_4 ions, the assimilation of NH^+_4 ions appeared to be blocked by MSX, as indicated by the cessation of growth, but the cells rapidly lost their mating ability. These results indicate that the NH^+_4 ion itself, and not some metabolite, controls gametic differentiation and dedifferentiation in C. reinhardtii.
日本植物生理学会の論文