Pollenkitt formation in Ilex paraguariensis A.St.Hil. (Aquifoliaceae) |
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| Authors: | R P Santos J E A Mariath M Hesse |
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| Institution: | (1) Department of Botany, Biosciences Institute, Federal University of Rio Grande do Sul, Porto Alegre, Brazil, BR;(2) Institute of Botany and Botanical Garden, University of Vienna, Wien, Austria, AT |
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| Abstract: | We investigated the cellular and organelle transformations during the formation of the pollenkitt in the secretory tapetum
of Ilex paraguariensis. After the dissolution of the callose surrounding the young microspores, the elaioplasts of the tapetum produce many globules
of saturated and unsaturated lipids (plastoglobules). Further on, oleosomes with unsaturated lipids, synthesized in the endoplasmic
reticulum, accumulate in the tapetal cytoplasm. In contrast to other species, the plastoglobule production seems to precede
the oleosome synthesis. The tapetum shows signs of cellular maturation in the late vacuolated microspore stage, when the plastoglobules
and oleosomes coalesce and form the pollenkitt mass. In mature stages of the tapetum the pollenkitt is released into the loculus.
Finally, it is mainly deposited on the exine, according to the entomophilous character of this species. The mode of pollenkitt
formation in Ilex para guariensis and its transfer to the pollen surface is slightly dissimilar to other Angiosperms.
Received October 24, 2002; accepted December 2, 2002 Published online: March 20, 2003 |
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| Keywords: | : Ilex paraguariensis maté Aquifoliaceae pollenkitt tapetum plastoglobules oleosomes |
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