The formation of resistant zygospores in the green alga Chlamydomonas reinhardtii

• Applicant: Professor Dr. Severin Sasso
• Subject Area: Plant Physiology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 448536062

Microscopic algae (microalgae) are important primary producers in aquatic and terrestrial ecosystems. During the sexual reproduction of many microalgae, the formation of zygotes is coupled to the subsequent development of zygotes into resistant, dormant spores. This developmental process lasts approximately one week and includes chlorophyll degradation and the assembly of a multilayered, protective cell wall. The resulting zygospores possess an astounding ability to withstand various forms of abiotic stress such as freezing or desiccation. In previous work, we have discovered the first gene essential for the maturation of early zygotes into robust zygospores in the model alga Chlamydomonas reinhardtii (Heimerl et al., Plant J. 95, 268-281 (2018)). In the current project, we want to study the zygote-to-zygospore transition more broadly at the molecular, genetic and physiological levels. In order to examine if the increase in dormancy coincides with the increase in environmental resistance, photosynthetic capacity and desiccation tolerance will be quantified over the course of zygospore development. Furthermore, the formation of a cell wall polymer critical for desiccation tolerance will be investigated, and additional genes required for zygospore maturation will be identified. The results of this project will help to understand how a eukaryotic photosynthetic cell can adapt its metabolism and turn into a resistant, inactive spore to survive under deteriorating environmental conditions.

• DFG Programme: Research Grants