Abstract:Two distinct genes, OsAgpS1 and OsAgpS2, were found to encode ADP-Glucose pyrophosphorylase small subunit in rice (Oryaz sativa L.) genome. While OsAgpS1 gives rise to two different transcripts, OsAgpS1a and OsAgpS1b, through alternative splicing at the first exon. The expression patterns of the two transcripts in different tissues and developing endosperms in rice were analyzed by RT-PCR. On the other hand, the spatial regulation of OsAgpS1gene expression by using a reporter gene GUS driven by two different promoters upstream the two transcripts, respectively, were analyzed. The results showed that OsAgpS1a transcripts and the reporter gene GUS driven by the OsAgpS1a promoter had a similar expression pattern that abundantly expressed in endosperms but very low in leaves, whereas OsAgpS1b transcripts and the reporter gene GUS driven by the OsAgpS1b promoter own other similar expression pattern that expressed at a low level in leaves, roots and early development endosperms of rice. These results suggested that these two different transcripts of OsAgpS1 gene were driven by different promoters, and the promoter upstream OsAgpS1a could be used as an endosperm specific expression promoter in rice.