Stimulation of precursor rRNA synthesis in the cotyledons of mustard seedlings by phytochrome

Thien, Wilfried; Schöpfer, Peter

doi:10.1007/bf00384765

Cited by 8 publications

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“…Experiments to confirm this conclusion on the level of precursor rRNA synthesis are in progress. A preliminary report dealing with this subject is published elsewhere (30). 56,1975 …”

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confidence: 99%

Control by Phytochrome of Cytoplasmic and Plastid rRNA Accumulation in Cotyledons of Mustard Seedlings in the Absence of Photosynthesis

Thien¹,

Schöpfer²

1975

Plant Physiol.

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Light stimulates the accumtulation of cytoplasmic and plastid rRNA in the cotyledons of mustard (Sinapis alba L.) seedlings. This effect is mediated by phytochrome. Continuous far red irradiation and brief red light pulses (the effect of which is reversible by brief far red light pulses) increase the amount of 1.3 X 106 + 0.7 X 106 and 1.1 X 101 + 0.56 X 106 molecular weight rRNA species. Large and small ribosomal subunit RNAs are maintained in a 1 :1 molar ratio in both cytoplasm and plastids, irrespective of seedling age and light treatment. Continuous white fluorescent light (which saturates chlorophyll synthesis) is less effective than contintuous far red light (essentially no chlorophyll synthesis) in producing the response, indicating that the accumulation of plastid rRNA is independent of the buildup of a functional photosynthetic apparatus. We conclude that the transcription of cytoplasmic and plastid rRNA cistrons is uinder phytochrome control.The involvement of phytochrome in the control of RNA metabolism of higher plants is well documented (2,10,20,27,32). So far there is no information regarding the species of RNA affected or the mechanism(s) by which the observed responses on the RNA level are produced. This situation is especially unsatisfactory because the only general hypothesis put forward until now to explain the phytochrome-mediated photomorphogenesis in molecular terms postulates specific derepression and repression of gene activities as a mechanism of phytochrome control. This "hypothesis of differential gene activation and gene repression" by Pfr (16,25)

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“…Experiments to confirm this conclusion on the level of precursor rRNA synthesis are in progress. A preliminary report dealing with this subject is published elsewhere (30). 56,1975 …”

mentioning

confidence: 99%

Control by Phytochrome of Cytoplasmic and Plastid rRNA Accumulation in Cotyledons of Mustard Seedlings in the Absence of Photosynthesis

Thien¹,

Schöpfer²

1975

Plant Physiol.

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“…A differential effect of red light on the nucleic acid synthesis in some cell organelles of pea has also been reported Phytochrome has been shown to control rRNA synthesis both in nuclei and chloroplasts of mustard cotyledons [186,187]. High intensity green light which facilitates spinach chloroplast growth and development, but with reduced chloroplast division, was shown to be without influence on plastid rRNA synthesis [ 1391.…”

Section: Nucleic Acidsmentioning

confidence: 99%