Cell Cycle Activation During Imbibition and Visible Germination in Embryos and Megagametophytes of Jack Pine (Pinus banksiana Lamb.) |
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Authors: | WYMAN, JANET TREMBLAY, M-FRANCINE LALIBERTE, SYLVIE |
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Affiliation: | Groupe de Recherche en Ecologie Forestière, Département des sciences biologiques, Université du Québec à Montréal, Case postale 8888, succursale Centre-Ville, Montréal (Québec), Canada, H3C 3P8 Département des sciences appliquées, Unité de recherche et de développement forestier de l'Abitibi-Témiscamingue, Université du Québec en Abitibi-Témiscamingue, Case Postale 700, Rouyn-Noranda (Québec), Canada, J9X 5E4 |
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Abstract: | Flow cytometric determination of cell cycle activation duringimbibition and visible germination in five families of jackpine (Pinus banksiana Lamb.) embryos and megagametophytes revealedthat in seeds that had undergone no imbibition the majorityof cells were in the 2C state. As the imbibition period increased,less of the nuclei were blocked in the G0/G1 state and morebecome active in the cell cycle. The augmentation in the nucleiactive in the 2C4C cycle as well as those with DNA levelshigher than the 4C state occured gradually and preceeded radicleemergence. In megagametophyte tissue examined at various stagesof imbibition, cell cycle activity became apparent rapidly followingimbibition. In nuclei of green and white embryos examined separatelythe 2frequency distributions were significantly different forall three families after 144h. As imbibition period increased,fewer nuclei from the green embryos were blocked in the 2C state,and more became active in the 2C4C cell cycle. This wasnot the case for white embryos where no significant linear relationwas noted. Cell cycle activity in the hypocotyl+cotyledons regionand the emerging radicle were examined separately. Functionalrelations found in the hypocotyl+cotyledons region were notevident in the radicle. As visible germination proceeded, cellcycle activity in the hypocotyl + cotyledons region for thisperiod of germination showed a reversal of the activity notedduring imbibition: fewer nuclei were active and once again ahigher proportion were found in the 2C state. cell cycle; C levels; DNA content; flow cytometry; germination; imbibition; jack pine; megagametophyte; Pinus banksiana Lamb |
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