Functional Identification And Expression Analysis Of Glucose-6-Phosphate-1-Epimerase In Dianthus Chinensis

Many enzymes involved in sugar metabolism are specific for the α or β anomer of their substrate.Therefore sugar anomerization equilibrium plays a role in the general metabolic fluxes of the cell.Being one of them,Glucose-6-phosphate-1-Epimerase(G6P1E)can catalyze the α or β changes of glucose-6-phosphate.The gene sequence annotated as the G6P1 E was obtained from the sequencing of Dianthus chinensis transcriptome.Its function was identified by Agrobacterium tumefaciens-mediated post-transcriptional gene silencing,and its gene expression profile was analyzed.The main results were as follows:1.In the sequencing of Dianthus chinensis transcriptome,the size of gene annotated as G6P1 E is 1401 bp,including an ORF of 1077 bp.It encodes 358 amino acid.The homology comparison on NCBI showed that the deduced amino acid sequence of G6P1 E was 74.26% similar to those of the other 8 plants.2.The pTRV2/DchG6P1 E expression vector was constructed.Flower buds of Dianthus chinensis stage flower buds at stage 2 were infected with Agrobacterium tumefaciens containing the recombinant plasmid.The petals’ color became lighter,especially the color inside the wreath.The gene expressions of Dch G6P1 E and the contents of anthocyanin decreased significantly in the silencing petals.The activity of G6P1 E enzymes decreased,about 80.79 ± 4.91% of the p TRV1+p TRV2(control).The glucose content decreased significantly.The results showed that the gene is related to the flower color of Dianthus chinensis.3.The expression profiles of DchG6P1E were analyzed by q RT-PCR.With the development of flower buds,the expression of Dch G6P1 E increased gradually.The expression at stage 2 was 2.54 times of the stage 1 and the stage 3 was 2.96 times of stage 1.The expression of Dch G6P1 E was different among the petals of three flower colors.The expression of Dch G6P1 E in white flowers with red circle was 1.85 times of white flowers,and the dark pink flowers was 2.54 times of white flowers.The expression of Dch G6P1 E in different organs was root > stem > flower > leaf.The expression in root,stem and flower was 28.85,8.36 and 2.18 times of leaf,respectively.4.Among the petals of five flower colors,the glucose content increased gradually with the deepening of flower color.There was no significant difference in glucose content among white flowers,white pink flowers and light pink petals.The glucose content in dark red petals was the highest,followed by deep pink.The glucose contents in both of them were significantly higher than those in the other three flowers color.In conclusion,the glucose content is consistent with the change of flower color.Being one of enzymes in sugar metabolism,Dch G6P1 E is related to the flower color in Dianthus chinensis.Consequently,Dch G6P1 E might work the flower color by changing the sugar content.