Cloning and expression analysis of and quantification of downstream products in under flooding stress / 中国中药杂志

To investigate the effects of the expression of flavonoid 3' hydroxylase gene ( and active ingredients in under flooding stress, we cloned F3'H from Hangju (temporarily named ) and conducted bioinformatics analysis. During the flower bud differentiation stage, we flooded the and then used the Real-time PCR to detect the relative expression of ; Finally, active ingredients of the inflorescence were measured by HPLC.The sequencing results showed that 1 562 bp sequence was acquired with the largest open reading frame of 1 527 bp, which encoded 508 amino acids. The phylogenetic tree found that was highly homologous to other species of Compositae. Real-time PCR results showed that had a significant response to flooding stress and had the highest expression level after flooding for 24 h, which was about 9 times as that of the control group. The results of HPLC showed that luteolin and luteoloside, the downstream products catalyzed by the F3'H, were significantly higher than those in the control group. It was also found that the contents of chlorogenic acid and 3,5- acid were also significantly higher than those of the control group. Therefore, regulates the synthesis of downstream products by regulating the expression of in the flavonoid synthesis pathway under flooding stress, thereby responding to flooding stress. The flooding stress during flower bud differentiation can significantly enhance the accumulation of active ingredients.

Prokaryotic expression and in vitro enzyme activity analysis of flavonol synthase in Chrysanthemum morifolium cv. 'Hangju' / 中国中药杂志

We cloned flavonol synthase gene (named as CmFLS) by RACE from Chrysanthemum morifolium cv. 'Hangju' based on transcriptome database. Sequencing results showed that 1 235 bp sequence was acquired with the largest open reading frame (ORF) of 1 008 bp, which encoded 335 amino acids. The predicted CmFLS encoded protein had an isoelectric point (pI) of 5.41. The phylogenetic tree analysis indicated that CmFLS was highly homologous to other FLSs, which identified from the species of Compositae. The recombinant fusion protein, with a molecular mass of 43 kDa, was successfully expressed by prokaryotic expression system. Meanwhile, Ni-NTA resin was used to purify the recombinant fusion protein, and the Ni-Native Buffer containing 250 mmol·L⁻¹ imidazole was most favorable for elution. The purified recombinant fusion protein was subjected to in vitro catalytic reaction, and then the products were extracted and analyzed by HPLC. The results showed that the recombinant fusion protein CmFLS was able to catalyze the production of quercetin by dihydroquercetin under specific buffer and reaction conditions, which indicated that the functional protein encoded by CmFLS had dioxygenase activity in the biosynthetic pathway of flavonoids biosynthesis in Ch. morifolium cv. 'Hangju'. The above results laid the foundation for further studying on CmFLS, and provided new ideas for the regulation of flavonoids metabolism from the molecular level and the catalytic synthesis of flavonols in vitro.