Identification of differentially expressed photosynthesis- and sugar synthesis-related genes in tomato (Solanum lycopersicum) plants grown under different CO2 concentrations

The aim of the present study was to identify key genes and molecular biological processes that are responsive to CO2 enrichment in tomato (Solanum lycopersicum L.). Tomato plants were exposed to CO2 concentrations of either 350-500 mu mol/mol (ambient) or 750-850 mu mol/mol, and genes that were differentially expressed (DEGs) in the two groups were identified. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were then used to identify DEGs involved in photosynthesis and sugar synthesis. As a result, a total of 208 DEGs, including 179 up-regulated and 29 down-regulated genes, were identified. GO functional annotation revealed that the DEGs were mainly enriched in the processes of photosystem I, photosystem II, photosynthesis phosphate ion binding, and electron carrier activity, whereas the KEGG pathway analysis indicated that the DEGs were mainly enriched in 21 signalling pathways, including plant hormone signal transduction, RNA polymerase, ribosomes and photosynthesis. A total of 62 DEGs, including Solyc12g032970.1, Solyc12g032960.1, Solyc07g043480.1 and Solyc02g086650.2, were associated with photosynthesis and sugar synthesis. The present study provides a basis for investigating the effects of elevated CO2 on the molecular processes of tomato, which will, in turn, provide a theoretical basis for tomato breeding programs.