Senescence vs. changes in nuclear DNA, protein and dry mass contents in leaf mesophyll of two species differing in occurrence of endomitotic polyploidy.
DNA and Naphtol yellow S-staining (F-NYS) protein contents were measured cytophotometrically using the Feulgen method in the nuclei of the mesophyll from the basal and apical zone of young and old leaves in two perennial monocotyledonous species: Rhoeo discolor and Clivia miniata, differing in presence or absence of DNA endoreplication. Dry mass content was determined interferometrically using an uniform field with large image shearing method. It has been shown that nuclei with 2C DNA and below 2C DNA content dominate in old leaves. The decrease in dry mass content of nuclei correlated with the decrease in NYS protein content. Parallelly a significant increase in NYS protein and DNA contents observed in chromocenters Rhoeo discolor was proportional to the increase in their dry mass. The decrease in nuclear DNA content in mesophyll of old leaves in endoreplicating species was the same as in non-edoreplicating one, however the senescence was more intensive in endoreplicating species.
Kuran
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Department of Plant Cytology, and Cytochemistry, University of Lódź, Poland.
D002467:Cell Nucleus / Q000378:metabolism; D016922:Cellular Senescence / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics; D018744:DNA, Plant / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics*; D010940:Plant Proteins / Q000378:metabolism*; D011003:Ploidies
D018744:DNA, Plant; D010940:Plant Proteins