|
|
||||||||
|
(American Journal of Botany. 2008;95:643-654.) doi: 10.3732/ajb.2007210 © 2008 Botanical Society of America, Inc. |
What's this? |
Anatomy and Morphology |
2 Cullman Program for Molecular Systematics Studies, New York Botanical Garden, Bronx, New York 10458 USA 3 Department of Botany, Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103 USA 4 Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742 USA
ABSTRACT
Patterns of cell division and cross wall formation vary among the charophytes, green algae closely related to land plants. One group of charophytes, the conjugating green algae (Zygnematophyceae), is species-rich and is known to vary substantially in the mode of cell division, but the details of these cell division patterns and their phylogenetic distribution remain poorly understood. We studied cross wall development in filamentous Desmidiaceae (a clade of conjugating green algae) using differential interference contrast and fluorescence light microscopy. All strains investigated had centripetal encroachment of a septum, but with several different developmental patterns. In most cases, cell wall formation was delayed with respect to the Cosmarium-type of cell division, and the cross wall was modified considerably after deposition in a manner specific to the particular clade of filamentous desmids. These characteristics were mapped on a phylogeny estimated from a data set of two organellar genes, and the evolutionary implications of the character state distribution were evaluated. The data suggest a complex history of evolution of cell division in this lineage and also imply that Desmidium and Spondylosium are polyphyletic. These results indicate that many features of the cell shape are determined at the time of cell division in conjugating green algae.
Key Words: Desmidiaceae cell division coxIII development rbcL septum formation Zygnematophyceae
Received for publication 8 July 2007. Accepted for publication 7 March 2008.
FOOTNOTES
1 This work was supported by NSF grant DEB-9978117 to C.F.D. and by a USDA-CSREES graduate training fellowship 2005-3842015761 to J.D.H.
5 Author for correspondence (e-mail: jhall{at}nybg.org)
![]()
CiteULike
Complore
Connotea
Del.icio.us
Digg
Facebook
Reddit
Technorati
Twitter What's this?
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |