Female gametophyte development and evolution in Piperales.

摘要

Piperales is an extremely diverse angiosperm lineage in terms of female gametophyte structure and has been the subject of several recent molecular phylogenetic analyses. This makes Piperales an excellent candidate clade for comparative investigations of female gametophyte developmental evolution. Aristolochiaceae, Saururaceae, and Piperaceae comprise Piperales, and in this investigation I describe female gametophyte development of Aristolochia labiata (Aristolochiaceae), Piper peltatum (Piperaceae), Peperomia dolabriformis (Piperaceae), Peperomia jamesoniana (Piperaceae), and Peperomia hispidula (Piperaceae). My data combine light and confocal microscopy with three-dimensional computer reconstructions, and allow me to describe aspects of female gametophyte development in Piperales that were previously unknown in angiosperms. We have also quantified the ploidy of several cell types in developing female gametophytes and seeds of Piperales.;The newly discovered nuclear position, division and wall formation events that we describe in female gametophytes of Piperales allow for the construction of explicit hypotheses of developmental evolution within Piperales, and more broadly throughout angiosperms. These hypotheses of plant female gametophyte developmental evolution in Piperales operate within a phylogenetic context, and provide a template for future comparative analyses of female gametophyte ontogeny in angiosperms.