Secondary Symbiotic Origin of Algal Plastids and the Phylogeny of the Bangiophycidae (Rhodophyta)

DEB-0107754

Debashish Bhattacharya

A grant has been awarded to Dr. Debashish Bhattacharya at the University of Iowa to determine the phylogeny, or evolutionary tree, of the red algae (Rhodophyta). The red algae are important primary producers and key players in the genesis of a multitude of other photosynthetic cells though a process termed secondary endosymbiosis. In secondary endosymbiosis, existing algae are engulfed by other single-celled protists and maintained indefinitely as photosynthetic machines (plastids) in the cell. Genes encoded in the plastid genomes of red algae and other algae containing red algal secondary endosymbionts (e.g., brown and cryptophyte algae) will be studied to determine how often secondary endosymbiosis has occurred, and which red alga was the donor of the plastid in the different algal groups. The red algal phylogeny will also be the basis for a much-needed taxonomic revision of the Rhodophyta.

The biodiversity of the algae is an infinite reservoir of organisms for fundamental biological research, and a resource for commercially important products. Furthermore, the algae are important suppliers of oxygen as well as consumers of carbon dioxide, a gas that contributes to the green-house effect. Although problems in algal biology have been studied to a much lesser extent than efforts devoted to 'model' systems, the advent of modern molecular biology has enabled scientists to broaden their scope of investigation to all life forms. The red algal project touches on two cornerstones of modern biological research, determining the biodiversity on our planet, and using taxa in nature to address fundamental questions about the origin and diversification of individual species and whole lineages. The red algal phylogeny will provide a firm basis for addressing issues in systematics and biodiversity, whereas the plastid gene tree will help us understand when and how often novel photosynthetic lineages have been created through secondary endosymbiosis.