title: Using natural selection to explore the adaptive potential of Chlamydomonas reinhardtii.
abstract: Improving feedstock is critical to facilitate the commercial utilization of algae, in particular in open pond systems where, due to the presence of competitors and pests, high algal growth rates and stress tolerance are beneficial. Here we raised laboratory cultures of the model alga Chlamydomonas reinhardtii under serial dilution to explore the potential of crop improvement using natural selection. The alga was evolved for 1,880 generations in liquid medium under continuous light (EL population). At the end of the experiment, EL cells had a growth rate that was 35% greater than the progenitor population (PL). The removal of acetate from the medium demonstrated that EL growth enhancement largely relied on efficient usage of this organic carbon source. Genome re-sequencing uncovered 1,937 polymorphic DNA regions in the EL population with 149 single nucleotide polymorphisms resulting in amino acid substitutions. Transcriptome analysis showed, in the EL population, significant up regulation of genes involved in protein synthesis, the cell cycle and cellular respiration, whereas the DNA repair pathway and photosynthesis were down regulated. Like other algae, EL cells accumulated neutral lipids under nitrogen depletion. Our work demonstrates transcriptome and genome-wide impacts of natural selection on algal cells and points to a useful strategy for strain improvement.
authors.affiliation: Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Marie-Mathilde
authors.initials: MM
authors.lastname: Perrineau
authors.affiliation: Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Jeferson
authors.initials: J
authors.lastname: Gross
authors.affiliation: Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Ehud
authors.initials: E
authors.lastname: Zelzion
authors.affiliation: Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Dana C
authors.initials: DC
authors.lastname: Price
authors.affiliation: Institute of Marine and Coastal Science, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Orly
authors.initials: O
authors.lastname: Levitan
authors.affiliation: Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Boyd
authors.affiliation: Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America; Institute of Marine and Coastal Science, Rutgers University, New Brunswick, New Jersey, United States of America.
authors.forename: Debashish
authors.initials: D
authors.lastname: Bhattacharya
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D012641:Selection, Genetic