EN
Sucrose is the principal form of photosynthesis products, and long-distance transport of sucrose requires sucrose transporters (SUTs) to perform loading and unloading functions. SUTs play an important role in plant growth, development and reproduction. In this study, five unique sucrose transporter (SbSUT) genes that contain full-length cDNA sequences were cloned from sweet sorghum, and these SbSUT genes were clustered into four different clades: SUT1, SUT3, SUT4 and SUT5. Heterologous expression of SbSUTs in yeast demonstrated that they were functional sucrose transporters. Tissue-specific expression profiles showed that sorghum SUT genes had different tissue-specific expression patterns, suggesting that sorghum SUT genes may play an important role in plant growth and developmental processes. After defoliation, expression patterns of SbSUT1, SbSUT2 and SbSUT4 were different in leaf sheaths, leaves and roots. Taken together, the results indicate that the above mentioned five unique sucrose transporter genes may play important roles in performing sucrose loading and unloading functions and that they exhibit different expression in response to leaf blade removal.