Phragmoplastins, the Trentepohliales, and the Evolution of the Cytokinesis in Green Plants

Abstract

AbstractGreen plants have been shown to have a common ancestor and to contain two lineages: the Chlorophytes and the Streptophytes, both encompassing representatives of the original ‘green algae’. The phragmoplast‐mediated cell division characterizes the land plants in the Streptophyte lineage and some basal green algal orders (Coleochaetales, Charales and Zygnematales). However, a well‐developed phragmoplast‐type cell division has been documented in two subaerial green algae (Cephaleuros parasiticus and Trentepohlia odorata) belonging to the order Trentepohliales, an order that molecular sequence data place unequivocally within the Chlorophytes (rather than Streptophytes). Is the phragmoplast‐mediated cell division of the Trentepohliales a case for homology or nonhomology? In order to reveal the answer to this question, we are exploring the potential phylogenetic information inferred from gene sequences of phragmoplastin, a dynamin‐like protein which has been demonstrated to be associated with cell plate formation during the phragmoplast‐mediated cytokinesis in land plants. Primers were designed based on an available phragmoplastin sequence from soybean, and yielded PCR amplifications from the green algae (Trentepohlia and Cephaleuros), a bryophyte (Bazzania) and land plants (Glycine and Arabidopsis). The evolutionary history of the development of the phragmoplast may remain in the analysis of the gene sequences for this group of proteins.