Genome-Wide Identification and Expression Analysis of SWEET Gene Family in Strawberry

The Sugars Will Eventually be Exported Transporter (SWEET) is a class of bidirectional sugar transporter that is involved in critical physiological processes such as plant growth and development, and its response to biotic and abiotic stresses. Currently, there are few reports on the SWEET gene family in strawberry. In this study, we mined the SWEET gene family members in Fragaria x ananassa 'Camarosa' and carefully analyzed their molecular features and expression patterns. The results showed that 77 FanSWEET genes existed in the F. x ananassa 'Camarosa' genome, and the phylogenetic analysis classified them into four sub-groups. Analysis of gene structure, conserved structural domains, and conserved motifs showed that FanSWEETs were highly conserved during the evolutionary process. Expression profiling of the 11 FanSWEET genes revealed that three members were highly expressed in strawberry fruits, which were presumed to be involved in sugar transport during strawberry fruit ripening. In addition, based on the exogenous sugar-spraying treatment and quantitative real-time PCR analysis, we found that different members responded to different sugar treatments in different response patterns, and their functions in sugar transport need to be further explored. The present study provides a reference for further analysis of the functions of the SWEET gene in strawberry.