Postmeiotic cytokinesis and pollen aperture number determination in eudicots: effect of the cleavage wall number |
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Authors: | Ressayre A Mignot A Siljak-Yakovlev S Raquin C |
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Institution: | (1) Laboratoire de Ecologie, Systematique et Evolution, Unité Mixte de Recherche du Centre National de la Recherche Scientifique, Université Paris Sud, Orsay, FR;(2) Laboratoire de Paléoenvironnements, Institut de Sciences de l'Evolution, Unité Mixte de Recherche du Centre National de la Recherche Scientifique, Université Montpellier 2, Montpellier, FR |
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Abstract: | Summary. In eudicot postmeiotic tetrads, apertures are usually joined in pairs in highly conserved areas. These appear to be located
at the last points of contact persisting at the end of cytokinesis between the cytoplasm of the future microspores. In order
to investigate the relationship between cytokinesis and aperture formation, aperture distribution within postmeiotic tetrads
and the progression of meiosis were studied in Nicotiana tabacum cv. Ambalema. This variety (inbred line) produces about 85% tricolporate pollen and 15% tetracolporate pollen grains. In
addition, about 7% of tetrads are composed of four equal-sized microspores and a supernumerary pseudomicrospore of small size
and an equal proportion of tetrads exhibit unpaired apertures (these apertures are not joined in pairs within tetrads). Observation
of cytokinesis indicates that both unpaired apertures and pseudomicrospores could result from the persistence of late communications
between microsporocytes. Observations of tetrads indicate that an increase in the number of elements that are separated during
cytokinesis is correlated with an increase in microspore aperture number. All data converge to support the hypothesis that
aperture site determination is partly controlled by the number of walls formed to separate the different elements of the tetrad.
Received May 22, 2002; accepted October 29, 2002; published online April 2, 2003
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ID="*" Correspondence and reprints: Laboratoire de Ecologie, Systematique et Evolution, Batiment 362, Université Paris Sud,
91405 Orsay cedex, France. |
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Keywords: | : Pollen Aperture pattern Meiosis Cytokinesis Tetrad Nicotiana tabacum |
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