siRNA mediated gene silencing in Fusarium sp. HKF15 for overproduction of bikaverin

•Secondary metabolite genes hmgR and fpps were silenced in Fusarium sp. HKF15.•Synthetic siRNAs were used to down-regulate carotenoid and gibberellin gene expression.•Bikaverin overproduction was achieved.•A strategy based on synthetic siRNAs for overproduction of desired metabolites is proposed.

Fusarium sp. HKF15 is an isolate from effluent treatment plant which produces bikaverin. Bikaverin is a polyketide having antitumor and antibiotic potential. Acetyl coenzyme A is a common precursor for bikaverin as well as carotenoids and gibberellins. A polyketide synthase gene bik1 is responsible for bikaverin production whereas, hydroxymethyl glutaryl coenzyme A reductase (hmgR) and farnesyl pyrophosphate synthase (fpps) are carotenoid and gibberellin pathway genes. Aim of this study was assessing siRNA mediated gene silencing for bikaverin overproduction with down-regulation of carotenoid and gibberellin pathway. HKF15 protoplasts derived from glucose grown culture were treated with 200 pmol ml−1hmgR and fpps siRNAs separately. Along with down-regulation of target genes, there was 2.4-fold increase in bik1 gene expression. The silencing was effective till 48 h with a 41% increase in bikaverin production. The study proposes a strategy for manipulation of physiology towards desired secondary metabolite overproduction.