Red algae (Rhodophyta) are important aquatic primary producers that are one of the most anciently diverged eukaryotic phyla with fossil remains dating back to 1.2 billion years ago. The red algal plastid is widespread in the tree of life as an engine of photosynthesis in microorganisms such as diatoms and red-tide forming dinoflagellates. Red algae are also sources of important human foods such as dulse and sushi wrap and have a multitude of pharmaceutical and industrial applications (e.g., agarose and carrageenans). In spite of their obvious importance, the evolutionary tree of life for red algae is poorly known. The aim of this research is to sample broadly across the major groups of red algae and reconstruct their phylogenetic history. To accomplish the aims of RedToL, the project will: 1) reconstruct a robust phylogeny of 471 red algal species using a combined dataset of 2 nuclear, 4 plastid, and 2 mitochondrial genes, 2) obtain complete sequences for a series of 16 plastid genomes that represent the taxonomic breadth of red algae, 3) make freely available red algal multi-gene and genome data via release to GenBank and a project-specific web site. The RedToL team, which consists of prominent red algal specialists from several generations and who use different methods (from morphology to phylogenomics), will address fundamental questions of red algal evolution and their place in the tree of life. This grant will support training of undergraduates, graduates, and post-doctoral fellows from underrepresented groups, including three international graduate students. The project results will be published in scientific papers and they will be discussed in two grant-supported summer workshops and two advisory board meetings. The workshops will focus on training students to become the next-generation of red algal taxonomists. The project team will also contribute to outreach efforts through various lectures and a dedicated RedToL website.
The photosynthetic red algae (Rhodophyta) play important roles in our lives yet most people are unaware of their existence. The ubiquitous sushi wrap is a red alga (Pyropia), the gelling agent in microbiology plates is from red algae (agar), and thickeners and stabilizers in ice cream and in pharmaceuticals come from red algae (carrageenan). Apart from these substantial contributions to human existence, red algae occupy a unique place in the field of evolutionary biology. This is because remnants of a red alga (named Bangiomorpha) provide the oldest recognizable fossils of a plant-like eukaryote that are present in rocks dated 1.2 billion years old. This tells us that photosynthesis was established in algae (and later land plants) at least 1 billion years ago. The RedToL project was inspired by these facts about red algae and the observations that these primary producers often dominate near-shore marine environments and that they provided the photosynthetic organelle (the plastid) to a wide variety of other algae through secondary endosymbiosis; i.e., a red alga was literally eaten by another cell and reduced to only its plastid, in famous species like diatoms and dinoflagellates. To explore the evolutionary history of red algae, we formed a consortium comprised of experts from different countries (Bhattacharya [US], Boo [South Korea], Fredericq [US], Hommersand [US], Lopez-Bautista [US], Saunders [Canada], Vis [US], and Yoon [US, currently in South Korea]) united under the RedToL banner. These senior scientists and their students and post-docs collected 550 species from culture collections and from nature and generated 10-gene sequences from all of them to erect a red algal tree of life. This is the most complete tree ever built of the red algae and will form the basis of taxonomic hierarchies for years to come that define the major clades in this lineage. We also generated 28 complete or partial genomes (nuclear, transcriptome, and organelle) to study how gene inventories have changed over a billion years of evolution. One of the most surprising findings of this gene "mining" exercise was that the common ancestor of red algae once lived in a highly specialized niche, such as those found in present-day Yellowstone National Park, and as a result, shed hundreds of genes to survive environmental stress. This billion year old "footprint" of Darwinian selection is still detectable in their DNA. All of this information has been published in more than 100 papers, presented at conferences and workshops, and the millions of bits of novel data we generated were made available at the national NCBI repository or at our project web site (http://dblab.rutgers.edu/redtol/). Senior scientists and students alike were trained in genomics and systematics and RedToL laid the foundation for the next generation of algal researchers who can use the plethora of novel data to develop tools for biotechnological, biomedical, and ecological applications.
