Project Details
Projekt
Evolution of biophysical carbon concentrating mechanisms from green algae to hornworts
Subject Area
Plant Genetics and Genomics
Term
since 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 440370236
Pyrenoids for biophysical carbon concentration (CCM) are present in most extant Streptophyte algae and in a distinct group of land plants, the hornworts. Preliminary data show that i) hornwort CCM is not an adaptation to atmospheric carbon fluctuations and ii) a constitutive mechanism, in which iii) hyperoxia upregulates CCM-like genes. These findings suggest that hornwort CCM is a relic of terrestrialization and an adaptation to flooding-desiccation cycles, allowing land-borne organisms like hornworts to thrive on land by keeping photosynthetic ability at optimal levels through an equilibrated oxygen:carbon supply. This hypothesis moves into light streptophytic algae CCM and prompts for comparative molecular and ultrastructural research of Strepthophyte algae and hornworts. Molecular components and functional features of CCM and pyrenoids of these enigmatic plant groups remain to be thoroughly investigated. Here, we will investigate the evolutionary trajectory of CCM and its contribution to terrestrialization from Chlorophyte through Streptophyte algae to hornworts. We hypothesize that the highly dynamic and inducible Chlorophyte green algal CCM has evolved into a constitutive form along the transition to land, which may have been advantageous by enabling increased photosynthetic rates under optimally permissive periods of the day. The evolutionary step towards more constitutive CCM may have occurred already in Streptophyte algae. To investigate this scenario, we study how inducibility of CCM has evolved by comparatively recording CO2 consumption, plastid ultrastructural changes, and associated transcriptomic and proteomic responses in the Chlorophyte green alga Chlamydomonas, the three Streptophyte algae Zygnema, Mesotaenium and Mougeotiopsis, and the two hornwort species Anthoceros agrestis and A. fusiformis. Furthermore, we will characterize and functionally validate candidate CCM genes using immunoprecipitation, CRISPR/Cas9 editing, and artificial microRNAs. This line of research on the CCM biology of Streptophyte algae and hornworts and its role along terrestrialization will answer how molecular adaptations contributed to organisms thriving under periodic flooding and drought, which is associated with highly fluctuating oxygen and carbon concentrations. Thus, our research program will shed new light onto the series of the succession and nature of molecular adaptations during early land plant evolution by highlighting the evolutionary-genetic plasticity with which plants, Streptophyte algae and hornworts in particular, cope with adverse environmental conditions.
DFG Programme
Priority Programmes
International Connection
Switzerland
