Abstract: A cDNA fragment S600 that shows differential expression pattern between a rice hybrid and its parental lines was identified by cDNA-AFLP. Northern blot results showed that the transcript level of S600 in female parent is lower than that in hybrid or male parent at both tillering and flowering stages. The transcript level in the two stages is different, indicating this gene is developmental-regulated. Homology search revealed that S600 is a part of coding sequence of rice sedoheptulose-J, 7-bisphosphatase. To obtain its complete coding sequence, S600 sequence was used to BLAST against Nipponbare cDNA database. Two highly homologous (99% identities) and functionally unknown cDNA clones (AK062089 and AK065773) were identified. Sequence analysis showed that both of the clones contain an identical open reading frame of (1179) bp that encodes 392 AAs SBPase precursor. The conservative amino acid residues involved in substrate binding and redox-regulation were found in the peptide. BLAST search result also indicates that SBPase gene is single locus in Nipponbare genome.