Comprehensive analysis of differentially expressed genes reveals the molecular response to elevated CO2 levels in two sea buckthorn cultivars

Atmospheric carbon dioxide (CO2) concentration increases every year. It is critical to understand the elevated CO2 response molecular mechanisms of plants using genomic techniques. Hippophae rhamnoides L. is a high stress resistance plant species widely distributed in Europe and Asia. However, the molecular mechanism of elevated CO2 response in H. rhamnoides has been limited. In this study, transcriptomic analysis of two sea buckthorn cultivars under different CO2 concentrations was performed, based on the next-generation illumina sequencing platform and de novo assembly. We identified 4740 differentially expressed genes in sea buckthorn response to elevated CO2 concentrations. According to the gene ontology (GO) results, photosystem I, photosynthesis and chloroplast thylakoid membrane were the main enriched terms in 'xiangyang' sea buckthorn. In 'zhongguo' sea buckthorn, photosynthesis was also the main significantly enriched term. However, the number of photosynthesis related differentially expressed genes were different between two sea buckthorn cultivars. Our GO and pathway analyses indicated that the expression levels of the transcription factors WRKY, MYB and NAC were significantly different between the two sea buckthorn cultivars. This study provides a reliable transcriptome sequence resource and is a valuable resource for genetic and genomic researches for plants under high CO2 concentration in the future.