Regulation of sesquiterpenoid metabolism in recombinant and elicited Valeriana officinalis hairy roots

• Published in: Phytochemistry (Oxford) Vol. 125; pp. 43 - 53
• Main Authors: Ricigliano, Vincent, Kumar, Santosh, Kinison, Scott, Brooks, Christopher, Nybo, S. Eric, Chappell, Joe, Howarth, Dianella G.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2016
• Subjects: Acetates - pharmacology; Agrobacterium; Alkyl and Aryl Transferases; Anti-Anxiety Agents - chemistry; Anti-Anxiety Agents - isolation & purification; beta-caryophyllene; biosynthesis; Caprofoliaceae; complementary DNA; Cyclopentanes - pharmacology; cytochrome P-450; DNA, Complementary - chemistry; gene overexpression; genes; germacrene; Humans; Indenes - chemistry; medicinal properties; metabolites; methyl jasmonate; Molecular Structure; Oxylipins - pharmacology; Plant Roots - chemistry; Polyisoprenyl Phosphates - chemistry; roots; Secondary metabolism regulation; sequence homology; Sesquiterpenes - analysis; Sesquiterpenes - chemistry; Sesquiterpenes - isolation & purification; Sesquiterpenoid; Valerian - chemistry; Valerian - genetics; Valerian root; Valeriana officinalis; Caprofoliaceae; RJZWGDPBGWGJNU-MTXIQXFFSA-N; NPNUFJAVOOONJE-GFUGXAQUSA-N; Agrobacterium; MZZFDMZYIBWOOA-KWCYVHTRSA-N; Valeriana officinalis; FEBNTWHYQKGEIQ-SUKRRCERSA-N; Secondary metabolism regulation; Valerian root; Sesquiterpenoid
• DOI: 10.1016/j.phytochem.2016.02.011
• ISSN: 0031-9422; 1873-3700

Binary vector co-transformation of Valeriana officinalis hairy roots and pathway-level metabolic analyses facilitated identification of key steps in the biosynthesis of pharmacologically active sesquiterpenoids valerenic acid, valerenal, valerenadiene and β-caryophyllene and their potential regulation. [Display omitted] •Binary vector co-transformation of Valeriana hairy roots was established.•Sesquiterpenoid metabolism was monitored by gene expression coupled with metabolic profiling.•Bottlenecks in sesquiterpenoid biosynthesis were identified using recombinant hairy root lines.•Metabolism is differentially regulated in response to gene overexpression and elicitation. The medicinal properties of Valerian (Valeriana officinalis) root preparations are attributed to the anxiolytic sesquiterpenoid valerenic acid and its biosynthetic precursors valerenal and valerenadiene, as well as the anti-inflammatory sesquiterpenoid β-caryophyllene. In order to study and engineer the biosynthesis of these pharmacologically active metabolites, a binary vector co-transformation system was developed for V. officinalis hairy roots. The relative expression levels and jasmonate-inducibility of a number of genes associated with sesquiterpenoid metabolism were profiled in roots: farnesyl pyrophosphate synthase (VoFPS), valerendiene synthase (VoVDS), germacrene C synthase (VoGCS), and a cytochrome P450 (CYP71D442) putatively associated with terpene metabolism based on sequence homology. Recombinant hairy root lines overexpressing VoFPS or VoVDS were generated and compared to control cultures. Overexpression of the VoFPS cDNA increased levels of the corresponding transcript 4- to 8-fold and sesquiterpene hydrocarbon accumulation by 1.5- to 4-fold. Overexpression of the VoVDS cDNA increased the corresponding transcript levels 5- to 9-fold and markedly increased yields of the oxygenated sesquiterpenoids valerenic acid and valerenal. Our findings suggest that the availability of cytoplasmic farnesyl diphosphate and valerenadiene are potential bottlenecks in Valeriana-specific sesquiterpenoid biosynthesis, which is also subject to regulation by methyl jasmonate elicitation.