Cloning and Characterization of Three Sugar Metabolism Genes (LBGAE, LBGALA, and LBMS) Regulated in Response to Elevated CO2 in Goji Berry (Lycium barbarum L.).

The composition and content of sugar play a pivotal role in goji berry (Lycium barbarum L.) fruits, determining fruit quality. Long-term exposure of goji berry to elevated CO2 (eCO2) was frequently demonstrated to reduce sugar content and secondary metabolites. In order to understand the regulatory mechanisms and improve the quality of fruit in the changing climate, it is essential to characterize sugar metabolism genes that respond to eCO2. The objectives of this study were to clone full-length cDNA of three sugar metabolism genes-LBGAE (Lycium barbarum UDP-glucuronate 4-epimerase), LBGALA (Lycium barbarum alpha-galactosidase), and LBMS (Lycium barbarum malate synthase)-that were previously identified responding to eCO2, and to analyze sequence characteristics and expression regulation patterns. Sugar metabolism enzymes regulated by these genes were also estimated along with various carbohydrates from goji berry fruits grown under ambient (400 μmol mol-1) and elevated (700 μmol mol-1) CO2 for 90 and 120 days. Homology-based sequence analysis revealed that the protein-contained functional domains are similar to sugar transport regulation and had a high sequence homology with other Solanaceae species. The sucrose metabolism-related enzyme's activity varied significantly from ambient to eCO2 in 90-day and 120-day samples along with sugars. This study provides fundamental information on sugar metabolism genes to eCO2 in goji berry to enhance fruit quality to climate change.