Abstract:

The full length cDNA of MrFRK2 was obtained by using RT-PCR and RACE amplification from Chinese bayberry（Myrica rubra Sieb. and Zucc.）‘Biqi’and‘Dongkui’fruit. MrFRK2 was 1 279 bp in full length and encoded a predicted protein of 332 amino acids（ORF length 996 bp），and flanked by 56 nucleotides at the 5′-UTR and 227 nucleotides at the 3′-UTR. The sequence homology comparison showed that，MrFRK2 containedthree conserved regions inherent to the pfkB family of carbohydrate kinases，an ATP-binding domain，and two substrate recognition domains. Phylogenetic analysis indicated that MrFRK2 shared the highest similarity with PtFRK2 with 85% homology. Furthermore，the changes of MrFRK2 expression，fructose and sucrose content during fruit ripening were investigated by q-PCR and HPLC analysis. Meanwhile，Dongkui fruit also experienced higher levels of fructose and lower sucrose-to-fructose ratio than in Biqi fruit. Correlation analysis showed fructose content was significantly negative correlation with the expression of MrFRK2 during ripening. Therefore，our results suggested that the higher fructose content in Dongkui fruit might be associated with lower levels of MrFRK2 expression，thereby increased the sucrose-to-fructose ratio in Biqi fruit during ripening.

Key words: Chinese bayberry, Myrica rubra Sieb. and Zucc., MrFRK2, fructose, fruit ripening