Our results demonstrate that selection using a serial dilution
regime can be used to substantially modify gene expression
patterns in C. reinhardtii. In the case of the faster growing EL
population, these cells can be manipulated to produce neutral
lipids, which is of interest to industry (e.g., [55]). The significant
growth enhancement in C. reinhardtii was largely supported by
improved acetate metabolism. This suggests that pathways of
organic carbon usage present in many algae may provide useful
targets for strain improvement. A large variety of DNA sequence
and gene expression differences, the latter for fundamental process
such as DNA replication and protein translation were uncovered
in the PL-EL comparison. Many questions however still remain
about our results such as the basis of the expression modification:
e.g., is the phenotype permanent or does it reflect long-term
acclimation due to epigenetic modification that can be reversed
over time? We also do not know yet the reproducibility of the EL
phenotype and if its underlying causes would be recapitulated in
independent cultures using the same treatment. These questions
are the targets of ongoing research in our lab. Nevertheless, our
results clearly demonstrate the enormous capacity of algal
genomes to adapt to changing conditions, a feature that can be
exploited to advance basic and applied research in microbial
eukaryotes.