title: Overexpression of the Saussurea medusa chalcone isomerase gene in S. involucrata hairy root cultures enhances their biosynthesis of apigenin.
abstract: Saussurea involucrata is a medicinal plant well known for its flavonoids, including apigenin, which has been shown to significantly inhibit tumorigenesis. Since naturally occurring apigenin is in very low abundance, we took a transgenic approach to increase apigenin production by engineering the flavonoid pathway. A construct was made to contain the complete cDNA sequence of the Saussurea medusa chalcone isomerase (CHI) gene under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Using an Agrobacterium rhizogenes-mediated transformation system, the chi overexpression cassette was incorporated into the genome of S. involucrata, and transgenic hairy root lines were established. CHI converts naringenin chalcone into naringenin that is the precursor of apigenin. We observed that transgenic hairy root lines grew faster and produced higher levels of apigenin and total flavonoids than wild-type hairy roots did. Over a culture period of 5 weeks, the best-performing line (C46) accumulated 32.1 mgL(-1) apigenin and 647.8 mgL(-1) total flavonoids, or 12 and 4 times, respectively, higher than wild-type hairy roots did. The enhanced productivity corresponded to elevated CHI activity, confirming the key role that CHI played for total flavonoids and apigenin synthesis and the efficiency of the current metabolic engineering strategy.
authors.affiliation: Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Feng-Xia
authors.initials: FX
authors.lastname: Li
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Jin
authors.forename: De-Xiu
authors.initials: DX
authors.lastname: Zhao
authors.forename: Li-Qin
authors.initials: LQ
authors.lastname: Cheng
authors.forename: Chun-Xiang
authors.initials: CX
authors.lastname: Fu
authors.forename: Fengshan
authors.initials: F
authors.lastname: Ma
mesh_terms: D047310:Apigenin / Q000096:biosynthesis* / Q000737:chemistry; D018533:Biomass; D005419:Flavonoids / Q000096:biosynthesis / Q000737:chemistry; D015870:Gene Expression / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D019753:Intramolecular Lyases / Q000235:genetics* / Q000378:metabolism*; D015394:Molecular Structure; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D030441:Saussurea / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic; D019076:Transgenes / Q000235:genetics
chemical_list: D005419:Flavonoids; D047310:Apigenin; D019753:Intramolecular Lyases; C019865:chalcone isomerase