Identification of the SWEET gene family and its relationship with soluble sugar content in wolfberry

[ Objective ] Sugars will eventually be exported transporters ( SWEETs ) play an important role in growth and development of plants. The aims of the study were to elucidate the role of the SWEET gene family in sugar accumulation during the development of wolfberry , and to provide a reference for revealing the role of the SWEET genes in the development of wolfberry fruits. [ Methods ] In the present study , based on genomic data of wolfberry , LbaSWEETs were identified by bioinformatics method , and the ex- pression of LbaSWEETs during fruit development was analyzed using published transcriptional data. [ Results ] There were 37 members of the SWEET gene family , which were randomly distributed on 10 chromosomes , encoding 152 621 amino acids. The molecular weight of the proteins was 16.87 69.97 kD , and the isoelectric point was 4.96 9.86. Subcellular localizations were predicted to be located in the chloroplast or plasma membrane , most containing seven transmembrane helices. Phylogenetic analysis showed that 37 LbaSWEET proteins were divided into 4 subgroups , which had similar gene structures and conserved motifs. Analysis of promoter elements showed that LbaSWEET promoters were rich in hor- mone response , stress response , and growth response elements. Transcriptome and qRT-PCR analysis showed that the expression of LbaSWEET9 and LbaSWEET29 genes was increased significantly with fruit ripening. Pearson correlation analysis showed that the expression levels of LbaSWEET9 and Lba- SWEET29 genes were significantly positively correlated with fructose content. [ Conclusion ] LbaSWEET9 and LbaSWEET29 are the key genes that may play an important role in the accumulation of fructose sugar.