Fragrance is a very important economic trait for rice cultivars. To identify the aroma genes in rice, we
performed a proteomics analysis of aroma-related proteins between Tainung 67 (TNG67) and its high
aroma mutant SA0420. Seventeen of the differentially identified proteins were close related with the
aroma phenotype of SA0420. Among them, 9 were found in leaves and 8 were found in grains. One protein (L3) was identified as the chloroplastic glyceraldehyde-3-phosphate dehydrogenase B (OsGAPDHB)
which was less abundant in SA0420 than TNG67. Sequence analysis demonstrated that this protein in
SA0420 carries a P425S mutation in the C-terminal extension domain, which might hinder the formation of holoenzyme, thereby changing the profile of aroma compounds. The protein profile of OsGAPDHB
showed only a weak correlation to its transcription profile. This result indicated that the reduction of
OsGAPDHB in SA0420 is regulated by post-translational processes and can only be analyzed by proteomics approach. Transgenic lines suppressing OsGAPDHB through RNAi harbored more fragrance than
TNG67 butless than SA0420.With betaine-aldehyde dehydrogenase as the only fragrance gene identified
in rice to date, OsGAPDHB may serve as the second protein known to contribute to the aroma phenotype.