Abstract: 【Objective】Alcohol production by using sweet sorghum (Sorghum bicolor L. Moench) might be an alternative way to provide energy for the world. To better understand the mechanism of sucrose accumulation, the correlation between sucrose content and sucrose phosphate synthetase (SPS) expression was analyzed by monitoring the expression of SPS in leaves (source) and stems (sink). 【Method】 The expression of SPS, the key enzyme of sucrose synthesis in sorghum, was investigated by using Western blot. 【Result】 The results indicated that the sucrose content, the expression of SPS in leaves and stems increased along with the growth of sorghum, reached the highest level at grain filling stage, and decreased at dough stage. The correlation coefficient between sugar content in stems of sweet sorghum and SPS protein expression in leaves was 0.895, and the correlation coefficient was 0.781 as compared with SPS protein expression in stems. In comparison of sweet and normal sorghums, there was no visible difference of SPS expression in leaves, while the SPS expression level in stems of sweet sorghum was much higher than that in normal sorghum. 【Conclusion】Sucrose is the major component of sugar in sorghum, sucrose accumulation was correlated with the expression of SPS in leaves and stems. In sweet sorghum, sucrose accumulation is correlated with the expression of SPS in stems.

Key words: sweet sorghum, normal sorghum, sucrose phosphate synthetase, western blot