Female Gametophyte and Early Seed Development in Peperomia (Piperaceae)

The evolution of female gametophyte development provides an example of how minor ontogenetic modifications can impact the functional biology of seeds. Mature Peperomia-type female gametophytes are normally depicted as 16-nucleate, nine-celled structures. However, recent ultrastructural data have dem...

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Bibliographic Details
Published in:American journal of botany 2010-01, Vol.97 (1), p.1-14
Main Authors: Madrid, Eric N., Friedman, William E.
Format: Article
Language:English
Subjects:
Anatomy and Morphology
Botany
Cell nucleus
Cell walls
development
Embryology
Endosperm
Evolution
Evolution & development
Evolutionary genetics
Female animals
female gametophyte
Fertilization
Flowers & plants
Gametophytes
Genetics
magnoliid
Ova
Peperomia
Piperaceae
Piperales
Seeds
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Summary:The evolution of female gametophyte development provides an example of how minor ontogenetic modifications can impact the functional biology of seeds. Mature Peperomia-type female gametophytes are normally depicted as 16-nucleate, nine-celled structures. However, recent ultrastructural data have demonstrated that many previous reports were incorrect, suggesting that our understanding of the Peperomia-type ontogeny is incomplete. In this investigation, female gametophyte and early seed development is described in Peperomia dolabriformis, P. jamesoniana, and P. hispidula. Nuclear positioning, nuclear division, and vacuole morphology are documented during the syncytial stages of development, and two mature female gametophyte cellular configurations are described. Endosperm ploidy is measured in each species using microspectrofluorometry. We conclude that a 10-celled construction is likely the most common cellular configuration in Peperomia and that a three-celled female gametophyte exists in P. hispidula. We also describe how developmental modifications of wall formation could produce the diverse cellular configurations observed throughout Peperomia. Interestingly, the onset of female gametophyte diversification within Piperales correlates with the origin of the perisperm in the common ancestor of Piperaceae + Saururaceae. We posit that the origin of the perisperm may have relaxed selection on endosperm genetic constructs, thereby promoting diversification of female gametophyte ontogeny.
ISSN:0002-9122
1537-2197
DOI:10.3732/ajb.0800423