Comparative ultrastructure of plasmodesmata of Chara and selected bryophytes: toward an elucidation of the evolutionary origin of plant plasmodesmata

We have used transmission electron microscopy to examine plasmodesmata of the charophycean green alga Chara zeylanica, and of the putatively early divergent bryophytes Monoclea gottschei (liverwort), Notothylas orbicularis (hornwort), and Sphagnum fimbriatum (moss), in an attempt to learn when seed...

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Bibliographic Details
Published in:American journal of botany 1997-09, Vol.84 (9), p.1169-1178
Main Authors: Cook, M.E, Graham, L.E, Botha, C.E.J, Lavin, C.A
Format: Article
Language:English
Subjects:
Algae
Botany
BRYOPHYTA
Bryophytes
CELL MEMBRANES
CELL STRUCTURE
CELL WALLS
Chara
CHARA ZEYLANICA
CHARACEAE
charophycean algae
CYTOPLASMIC ORGANELLES
ENDOPLASMIC RETICULUM
ESTRUCTURA CELULAR
EVOLUCION
EVOLUTION
Flowers & plants
HORNWORTS
LIVERWORTS
MEMBRANAS CELULARES
MEMBRANE CELLULAIRE
Monoclea
MONOCLEA GOTTSCHEI
Mother cells
Notothylas
NOTOTHYLAS ORBICULARIS
ORGANITE CELLULAIRE
ORGANULOS CITOPLASMICOS
PARED CELULAR
PAROI CELLULAIRE
Plant cells
plant evolution
Plants
PLASMA MEMBRANES
Plasmodesmata
RETICULO ENDOPLASMATICO
RETICULUM ENDOPLASMIQUE
Scientific imaging
Seeds
SPHAGNUM
SPHAGNUM FIMBRIATUM
STRUCTURE CELLULAIRE
ULTRAESTRUCTURA
ULTRASTRUCTURE
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Summary:We have used transmission electron microscopy to examine plasmodesmata of the charophycean green alga Chara zeylanica, and of the putatively early divergent bryophytes Monoclea gottschei (liverwort), Notothylas orbicularis (hornwort), and Sphagnum fimbriatum (moss), in an attempt to learn when seed plant plasmodesmata may have originated. The three bryophytes examined have desmotubules. In addition, Monoclea was found to have branched plasmodesmata, and plasmodesmata of Sphagnum displayed densely staining regions around the neck region, as well as ring-like wall specializations. In Chara, longitudinal sections revealed endoplasmic reticulum (ER) that sometimes appeared to be associated with plasmodesmata, but this was rare, despite abundant ER at the cell periphery. Across all three fixation methods, cross-sectional views showed an internal central structure, which in some cases appeared to be connected to the plasma membrane via spoke-like structures. Plasmodesmata were present even in the incompletely formed reticulum of forming cell plates, from which we conclude that primary plasmodesmata are formed at cytokinesis in Chara zeylanica. Based on these results it appears that plasmodesmata of Chara may be less specialized than those of seed plants, and that complex plasmodesmata probably evolved in the ancestor of land plants before extant lineages of bryophytes diverged
ISSN:0002-9122
1537-2197
DOI:10.2307/2446040