EFFECT OF CO2 CONCENTRATION ON THE TRANSCRIPTOME PROFILE IN MICROALGA Chlorella pyrenoidosa  

In order to enrich our knowledge of CO₂ concentrating mechanisms (CCM) in the eukaryotic algae, we used high-throughput sequencing technology to acquire transcriptome profiles at different CO₂ levels in unicellular green alga Chlorella pyrenoidosa. Altogether 53.86M and 62.10M clean short reads of 100 nt were obtained by Illumina sequencing from algae cultured at 4-fold air CO₂ and air CO₂ concentrations, respectively. A total of 32,662 unigenes were assembled from the two pooled samples. With an E-value cut-off of 1e-5, 7348, 5954 and 9092 unigenes were annotated in Gene Ontology (GO), Eukaryotic Orthologous Groups of proteins (KOG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, respectively. After screening, 51 differentially expressed unigenes were up-regulated and 8 were down-regulated in air CO₂ group, 4-fold air CO₂ group as the control. Eight differentially-expressed unigenes were validated their transcript levels by real-time quantitative PCR. Of them, thioredoxin-like protein, Laminin subunit beta-1 and Chlorophyll a/b binding protein might be associated with the utilizing of inorganic carbon at air CO₂ level.