Dissertation Project
My Ph.D. project is focused on investigating desiccation tolerance mechanisms in a genus of unicellular green algae Tetradesmus, which includes aquatic species as well as terrestrial ones, some of which come from deserts. The close relationship between the algae from such different habitats allows me to compare the response to drying and re-wetting across aquatic and desert algae, which is harder or not possible in many other groups (such as land plants).
After establishing relationships among the available species of Tetradesmus (Terlova & Lewis 2019) I carried out an assay to record algal response to drying in various conditions, using chlorophyll fluorescence as a proxy for cell physiological activity (Terlova et al. 2021). I discovered that
- desert algae are capable of recovering after drying, and they do it in just a few minutes! It is very impressive, desert grasses, for example, take hours to days to do the same;
- aquatic algae don’t recover from severe desiccation, but one strain did re-bounce when the stress was mild and slow; this is interesting because it potentially indicates that the last ancestor that the desert and aquatic algae shared (which was likely itself aquatic) might have had a certain “toolkit”, that was enhanced in desert algae, allowing them to adapt to their harsh environment.
Currently I am working on undestanding of molecular mechanisms behind desiccation tolerance in desert Tetradesmus in comparison to their aquactic sister-species. I am approaching this question by studying changes in gene expression during desiccation and rehydration, and changes in abundance of small molecules (metabolites). This duel approach will allow me to start connecting the genetic makeup of these algae with the phenotypical changes in their cells. The comparative aspect of this study (desert vs aquatic species) will tell us if even aquatic members of Tetradesmus have some necessary components of desiccation tolerance, i.e. a toolkit mentioned above.