Changes in the Cryptomeria japonica shoot transcriptome after short-term treatments with different concentrations of CO₂

Abstract

A transcriptome analysis was conducted to identify and characterize the differentially expressed genes (DEGs) in Cryptomeria japonica, a coniferous species endemic to Japan, after short-term treatments with different concentrations of CO₂. The de novo assembly of the obtained RNA reads resulted in 35,211 tentative transcripts. The expression levels of 113 and 30 genes were increased in response to elevated (800 ppm) and lowered (200 ppm) CO₂ concentrations, respectively. The deduced functions of these genes indicated that different molecular pathways were activated in response to the two different CO₂ treatments. The expression levels of the gene transcripts involved in the photosynthesis and photorespiration pathways were not affected by the CO₂ concentration, except for a homolog of a chloroplast RNA polymerase subunit that is involved in the transcription of chloroplast coding genes. Together with the enrichment of genes acting in chloroplasts among detected DEGs, adjusting the transcription of genes related to chloroplast functions may be one of the earliest responses to change CO₂ at the transcriptional level.