| Pyrimidine nucleotide and nucleic acid synthesis in embryos and megagametophytes of white spruce (Picea glauca) during germination. | |
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MedLine Citation:
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PMID: 12010479 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Pyrimidine nucleotide synthesis was investigated in isolated germinating zygotic embryos and separated megagametophytes of white spruce by following the metabolic fate of 14C-labelled orotic acid, uridine, and uracil, as well as by measuring the activities of the major enzymes participating in nucleotide synthesis. The rate of nucleic acid synthesis in these tissues was also examined by tracer experiments and autoradiographic studies conducted with labelled thymidine, and by conventional light microscopy. From our results, it emerges that changes in the contribution of the de novo and salvage pathways of pyrimidines play an important role during the initial stages of zygotic embryo germination. Preferential utilization of uridine for nucleic acid synthesis, via the salvage pathway, was observed at the onset of germination, before the restoration of a fully functional de novo pathway. Similar metabolic changes, not observed in the gametophytic tissue, were also documented in somatic embryos previously. These alterations of the overall pyrimidine metabolism may represent a strategy for ensuring the germinating embryos with a large nucleotide pool. Utilization of 14C-thymidine for nucleic acid synthesis increased in both dissected embryos and megagametophytes during germination. Autoradiographic and light microscopic studies indicated that soon after imbibition, DNA synthesis was preferentially initiated along the embryonic axis, especially in the cortical cells. Apical meristem reactivation was a later event, and the root meristem became activated before the shoot meristem. Taken together, these results indicate that precise changes in nucleotide and nucleic acid metabolism occur during the early phases of embryo germination. |
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Authors:
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Claudio Stasolla; Natalia Loukanina; Hiroshi Ashihara; Edward C Yeung; Trevor A Thorpe |
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Publication Detail:
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Type: JOURNAL ARTICLE |
Journal Detail:
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Title: Physiologia plantarum Volume: 115 ISSN: 1399-3054 ISO Abbreviation: Physiol Plant Publication Date: 2002 May |
Date Detail:
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Created Date: 2002-May-15 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 1256322 Medline TA: Physiol Plant Country: - |
Other Details:
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Languages: ENG Pagination: 155-165 Citation Subset: - |
Affiliation:
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Plant Physiology Research Group, Department of Biological Sciences, University of, Calgary, Calgary, Alberta T2N 1N4, Canada Department of Biology, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan Present address: NC State, Forest Biotechnology Group, 2500 Partners II Bldg., Raleigh, NC 27695, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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