Overexpression of the Arabidopsis thaliana squalene synthase gene in Withania coagulans hairy root cultures
Squalene synthase (SS) dimerizes two molecules of farnesyl diphosphate to synthesize squalene, a shared precursor in steroid and triterpenoid biosynthesis in plants. The SS1 gene encoding SS from Arabidopsis thaliana was introduced in Withania coagulans under the control of the CaMV35S promoter together with the T-DNA of Agrobacterium rhizogenes A4. The engineered hairy roots were studied for withanolide production and phytosterol accumulation and the results were compared with those obtained from control roots harbouring only the T-DNA from pRiA4. The increased capacity of the engineered roots for biosynthesizing phytosterols and withanolides was strongly related with the expression level of the transgene, showing the effectiveness of overexpressing 35SS1 to increase triterpenoid biosynthesis.
Additional key wordsAgrobacterium rhizogenes phytosterols Solanaceae withaferin A withanolide A
cauliflower mosaic virus
high performance liquid chromatography
Murashige and Skoog
polymerase chain reaction
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We thank the Serveis Cientificotècnics of the University of Barcelona for their support and Dr. Boronat’s group for the construction of the pBIs SS1 vector. This research has been supported by grants from the Spanish MEC and Generalitat of Catalonia (BIO2005-05583; BIO2008-01210; 2009 SGR 1217).
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