PT  - JOURNAL ARTICLE
AU  - Vilarrasa-Blasi, Josep
AU  - Fauser, Friedrich
AU  - Onishi, Masayuki
AU  - Ramundo, Silvia
AU  - Patena, Weronika
AU  - Millican, Matthew
AU  - Osaki, Jacqueline
AU  - Philp, Charlotte
AU  - Nemeth, Matthew
AU  - Salomé, Patrice A.
AU  - Li, Xiaobo
AU  - Wakao, Setsuko
AU  - Kim, Rick G.
AU  - Kaye, Yuval
AU  - Grossman, Arthur R.
AU  - Niyogi, Krishna K.
AU  - Merchant, Sabeeha
AU  - Cutler, Sean
AU  - Walter, Peter
AU  - Dinneny, José R.
AU  - Jonikas, Martin C.
AU  - Jinkerson, Robert E.
TI  - Systematic characterization of gene function in a photosynthetic organism
AID  - 10.1101/2020.12.11.420950
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.12.11.420950
4099  - http://biorxiv.org/content/early/2020/12/11/2020.12.11.420950.short
4100  - http://biorxiv.org/content/early/2020/12/11/2020.12.11.420950.full
AB  - Photosynthetic organisms are essential for human life, yet most of their genes remain functionally uncharacterized. Single-celled photosynthetic model systems have the potential to accelerate our ability to connect genes to functions. Here, using a barcoded mutant library of the model eukaryotic alga Chlamydomonas reinhardtii, we determined the phenotypes of more than 58,000 mutants under more than 121 different environmental growth conditions and chemical treatments. 78% of genes are represented by at least one mutant that showed a phenotype, providing clues to the functions of thousands of genes. Mutant phenotypic profiles allow us to place known and previously uncharacterized genes into functional pathways such as DNA repair, photosynthesis, the CO2-concentrating mechanism, and ciliogenesis. We illustrate the value of this resource by validating novel phenotypes and gene functions, including the discovery of three novel components of a defense pathway that counteracts actin cytoskeleton inhibitors released by other organisms. The data also inform phenotype discovery in land plants: mutants in Arabidopsis thaliana genes exhibit similar phenotypes to those we observed in their Chlamydomonas homologs. We anticipate that this resource will guide the functional characterization of genes across the tree of life.Competing Interest StatementThe authors have declared no competing interest.