Evidence against the involvement of DNA synthesis in phytochrome-mediated photomorphogenesis
E Mösinger1, K Bolze, P Schopfer
1Biologisches Institut II der Universität, Schänzlestrasse 1, D-7800, Freiburg, Federal Republic of Germany.
Abstract:
In order to clarify the relationship between photomorphogenesis and DNA replication we investigated the effect of continuous far-red or white light on the synthesis of DNA in the cotyledons and the hypocotyl of mustard seedlings between 36 and 108 h after sowing. The total DNA content of the cotyledons (about 2.2 pg cell(-1)) did not significantly change during this period although long-term labeling experiments revealed newly synthesized DNA of nuclear, plastid, and mitochondrial origin. Light had no detectable effect on total DNA content and on the labeling of either DNA fraction. Histoautoradiography indicated that nuclear DNA synthesis was exclusively localized in dividing stomatal cells and in sieve tube companion cells undergoing endopolyploidization. The DNA content of the hypocotyl increased continuously but likewise showed no detectable effect of light. It is concluded that cell growth and differentiation during photomorphogenesis is independent of DNA synthesis.
More Related Videos
Related Concept Videos
Biological Clocks and Seasonal Responses
Photoreceptors and Plant Responses to Light
Cell Signaling in Plants
The Antenna Complex
The Z-Scheme of Electron Transport in Photosynthesis
Light Acquisition


