Abstract: Total RNAs from the suspension cell line, callus, redifferentiatied callus and regenerated plantlets of rice (Oryza sativa L. ssp. indica) "Zhenshan 97B" were reverse-transcribed with poly (T) primers. The cDNAswere amplified by a pair of poly (T) primers and MADS (MCM1-Ag- amous-Deficiens-SRF) domain-specific primers and then separated on a sequencing gel. Several differentially expressed cDNA fragments were isolated. Sequencing of RMI, one of the differentially expressed gene cDNA fragments, showed that it contained a MADS domain, the primary structure of which shared a 63 % homology with the typical MADS-box agamous protein of Arabidopsis thaliana. Computer analysis also indicated that the secondary structure of RMI peptide was significantly similar to that of agamous protein. It was shown that RMi belonged to the MADS-box gene family. Molecular hybridization showed that RMI was silent in the suspension cells, while active in the callus, redifferentiated callus and regenerated plantlets.

Key words: Rice, mRNA differential display, MADS domain, Cell differentiation