Control of Mitosis by Phytochrome and a Blue-Light Receptor in Fern Spores

Abstract

The first mitosis in spores of the fern A. capillus-veneris was observed under a microscope equipped with Nomarski optics with irradiation from a safelight at 900 nm, and under a fluorescent microscope after staining with 4',6-diamidino-2-phenylindole. During imbibition the nucleus remained near one corner of each tetrahedron-shaped dormant spore, and asymmetric cell division occurred upon brief irradiation with red light. This red lightinduced mitosis was photoreversibly prevented by subsequent brief exposure to far-red light and was photo-irreversibly prevented by brief irradiation with blue light. However, neither farred nor blue light affected the germination rate when spores were irradiated after the first mitosis. Therefore, the first mitosis in the spores appears to be the crucial step for photoinduction of spore germination. Furthermore, experiments using a microbeam of red or blue light demonstrated that blue light was effective only when exposed to the nucleus, and no specific intracellular photoreceptive site for red light was found in the spores. Therefore, phytochrome in the far-red absorbing form induces the first mitosis in germinating spores but prevents the subsequent mitosis in protonemata, whereas a blue-light receptor prevents the former but induces the latter.

Light Differentially Regulates Cell Division and the mRNA Abundance of Pea Nucleolin during De-Etiolation

“…The data about R-induced cell division changes in flowering plants come from studies measuring the differences in cell size many hours after irradiation (Cosgrove, 1994). The only detailed study of phytochrome-mediated cell division kinetics is in germinating fern spores (Furuya et al, 1997). Prior to the work presented here, the relative kinetics of light-induced changes in cell division that occur during de-etiolation were not well documented.…”

Comparative studies on the photosynthetic characteristics of two maize (Zea mays L.) near-isogenic lines differing in their susceptibility to low light intensity

“…However, diffuse light can be more efficiently absorbed by a crop, and can compensate for reductions in direct light, and ultimately, reinforce crop leaf CO 2 assimilation and photoassimilation (Cohan et al, 2002). In addition, under shaded conditions, the proportions of the spectrum are altered, with an increase in blue light and a reduction in red light content (Bell et al, 2000), all factors which influence the growth and development of plants (Casal, 1988;Barnes and Bugbee, 1992;Furuya et al, 1997).…”

Assembly of Synthetic Locked Phycocyanobilin Derivatives with Phytochrome in Vitro and in Vivo in Ceratodon purpureus and Arabidopsis

“…Spore germination of ferns is another phytochrome response that can be monitored at the cellular level (Haupt, 1992;Furuya, et al, 1997). Here, we tested for the effect of 15EaPCB on Adiantum venustum spore germination.…”