Evolution of salt tolerance in a laboratory reared population of Chlamydomonas reinhardtii.

Environmental microbiology

PubMedID: 24373049

Perrineau MM, Zelzion E, Gross J, Price DC, Boyd J, Bhattacharya D. Evolution of salt tolerance in a laboratory reared population of Chlamydomonas reinhardtii. Environ Microbiol. 2013;.
Understanding the genetic underpinnings of adaptive traits in microalgae is important for the study of evolution and for applied uses. We used long-term selection under a regime of serial transfers with haploid populations of the green alga Chlamydomonas reinhardtii raised in liquid TAP medium containing 200 mM NaCl. After 1,255 generations, evolved salt populations (ES) could grow as rapidly in high salt medium as progenitor cells (PL). Transcriptome data was analyzed to elucidate the basis of salt tolerance in ES cells when compared to PL cells and to cells incubated for 48h in high salt medium (PS, the short-term acclimation response). These data demonstrate that evolved and short-term acclimation responses to salt stress differ fundamentally from each other. PS cells exhibit well-known responses to salt stress such as reduction in photosynthesis, up regulation of glycerophospholipid signaling, and up regulation of the transcription and translation machinery. In contrast, ES cells show down regulation of genes involved in the stress response and in transcription/translation. Our results suggest that gene-rich mixotrophic lineages such as C. reinhardtii may be able to adapt rapidly to abiotic stress engendered either by a rapidly changing climate or physical vicariance events that isolate populations in stressful environments.