A proteomic study of rice cultivar TNG67 and its high aroma mutant SA0420

•Unique mutant: SA0420 is a unique aroma mutant derived from the non-aromatic TNG67 rice variety by sodium azide mutagenesis.•Effective approach: The identified fragrance gene, GAPDHB in SA0420, is regulated in post-translational level and might only be identified by proteomics strategy.•New gene and pathway for rice aroma production: With BAD as the only identified fragrance gene to date, in the present study we proved GAPDHB gene could be another one for aroma production in rice by gene cloning, sequencing, and RNAi strategy. 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 but less 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.