Cloning and quantification of expression levels of two MADS-box genes from Momordica charantia

MADS-box genes are known to be important for the development of flowers. Two MADS-box genes (MCAG2 and MCAG6) were isolated from Momordica charantia female bud based on the MADS-box conserved sequences. The complete cDNA sequences of MCAG2 and MCAG6 encode a 231 and a 247 amino acid protein, respectively. Sequence comparison and phylogenetic analysis showed that MCAG2 and MCAG6 had high identities of amino acid with AG-like and AGL6-like genes, respectively. The alignment of the deduced amino acid sequence of AGL6-like genes revealed that there were two highly conserved regions in the C-terminus which were designated AGL6 motif I and AGL6 motif II. Phylogeny reconstructions suggested that AGL6-like genes were divided into three major clades. RT-PCR analysis of the MCAG2 and MCAG6 genes showed that they were both expressed in floral organs at different levels. However, MCAG6 was also expressed highly in shoot apex. Quantitative real-time reverse transcriptase-polymerase chain reaction analysis indicated that the expression of MCAG2 was detected at high levels in carpel, whereas MCAG6 was detected at high levels in shoot apex. The gene expression patterns suggest that MCAG2 and MCAG6 have a role in regulating bitter gourd floral development.