A marineChlamydomonassp. emerging as an algal model

Abstract

The freshwater microalga Chlamydomonas reinhardtii, which lives in wet soil, has served for decades as a model for numerous biological processes, and many tools have been introduced for this organism. Here, we have established a stable nuclear transformation for its marine counterpart, Chlamydomonas sp. SAG25.89, by fusing specific cis‐acting elements from its Actin gene with the gene providing hygromycin resistance and using an elaborated electroporation protocol. Like C. reinhardtii, Chlamydomonas sp. has a high GC content, allowing reporter genes and selection markers to be applicable in both organisms. Chlamydomonas sp. grows purely photoautotrophically and requires ammonia as a nitrogen source because its nuclear genome lacks some of the genes required for nitrogen metabolism. Interestingly, it can grow well under both low and very high salinities (up to 50 g · L‐1) rendering it as a model for osmotolerance. We further show that Chlamydomonas sp. grows well from 15 to 28°C, but halts its growth at 32°C. The genome of Chlamydomonas sp. contains some gene homologs the expression of which is regulated according to the ambient temperatures and/or confer thermal acclimation in C. reinhardtii. Thus, knowledge of temperature acclimation can now be compared to the marine species. Furthermore, Chlamydomonas sp. can serve as a model for studying marine microbial interactions and for comparing mechanisms in freshwater and marine environments. Chlamydomonas sp. was previously shown to be immobilized rapidly by a cyclic lipopeptide secreted from the antagonistic bacterium Pseudomonas protegens PF‐5, which deflagellates C. reinhardtii.

Multi-omics analysis of green lineage osmotic stress pathways unveils crucial roles of different cellular compartments

“…Halophytes, which are plants tolerant to high-sodium soils, represent an exception as they have evolved distinct mechanisms to handle intracellular osmolytes 50 . Recent identification of marine Chlamydomonas support the strong sodium detoxifying mechanism present in this algae 78 , and suggest that algae P2C Na + /K + -ATPase can be used to engineer salt tolerant land plants as previously hypothesized 79 . Chlamydomonas uses the contractile vacuole, an ancient organelle present in freshwater protists without cell walls, to remove excess intracellular water under hypoosmotic stress 13 .…”

moving toward more model algae

“…A major accomplishment presented in the manuscript by Carrasco Flores et al. (2021) is the generation of a transformation system for the green alga Chlamydomonas sp. SAG25.89 ( Chlamydomonas sp.…”

“…The work highlighted in the manuscript by Carrasco Flores et al. (2021) involves the marine strain, Chlamydomonas sp. SAG25.89 ( Chlamydomonas sp.…”

Exchange or Eliminate: The Secrets of Algal-Bacterial Relationships

“…Here, we have selected exemplary model species of micro- and macroalgae from terrestrial, freshwater, and marine environments and will present the current knowledge about their relationships with bacteria ( Figure 1 ). We are aware that more model species have emerged; however, these are beyond the scope of this review (e.g., [ 2 , 82 , 83 ]).…”