Flavonoid production and antioxidative activity in liquid-cultured hairy roots of Apocynum venetum

Apocynum venetum is a traditional and popular Chinese herb used for medicine and tea, and its major bioactive components is flavonoid. This study aimed to analyze the flavonoid production and antioxidative activity of the hairy roots under 250 mL shake flask and 3 L bubble bioreactor cultivation. Agrobacterium rhizogenes strain Ar.1193 was used to induce hairy roots at the wounding site of Apocynum venetum stems, and a 69.17% genetic transformation rate was noted. Hairy roots with the most vigorous growth were selected to analyze growth and flavonoid production over one complete growth cycle (30 d). The dry weight of the roots increased tenfold, flavonoid contents peaked at 25 d under shake flask and bioreactor cultivation, and the flavonoid content of roots in the bioreactor was 43.97% higher than that of roots in the shake flask. The flavonoid content and antioxidative activity of liquid-cultured hairy roots were significantly higher than those of field-planted roots, tissue-cultured plant roots, and callus. Moreover, a total of 117 flavonoids were detected in hairy roots. The results of the present study highlight hairy roots of Apocynum venetum could serve as an alternative to whole plants and may be used for the large-scale production of flavonoid.