Rendiconti Lincei

, Volume 28, Issue 4, pp 731–741 | Cite as

RNAi-mediated modulation of squalene synthase gene expression in Artemisia annua L. and its impact on artemisinin biosynthesis

  • Athar Ali
  • Malik Mobeen Ahmad
  • Mather Ali Khan
  • Parul Saxena
  • Shazia Khan
  • Malik Zainul Abdin


Artemisinin, an endoperoxide sesquiterpene lactone, is an antimalarial phytoconstituent isolated from Artemisia annua L. plants. Artemisinin-based combination therapies (ACTs) are recommended by WHO for treating malaria caused by multidrug-resistant Plasmodium falciparum sp. The main cause of instability in supply and cost escalation of ACTs in countries endemic to malaria is low content (0.01–1.1%) of artemisinin in these plants. In this study, the expression of SQS gene encoding squalene synthase (SQS), a key enzyme of the sterol biosynthetic pathway that competes for carbon precursor with that of artemisinin biosynthetic pathway was suppressed by hpRNAi-technology in A. annua to study its impact on artemisinin biosynthesis. Southern blot analyses of transgenic lines obtained have shown single (TR2, TR4 and TR10) and multiple copies (TR1, TR3, TR7, TR8 and TR9) of transgenes in their genomes. The GC/MS analysis showed decreased in squalene content by 65.7%, while HPLC result showed an increase in artemisinin content by 40.2% in transgenic lines, TR3. The plants from TR3 were also grown in environmentally controlled polyhouse and yielded 28.3% higher artemisinin as compared to the non-transgenic plants. The increased artemisinin levels coupled with reduced squalene contents in the transgenic lines of A. annua were well correlated with the up-regulation of artemisinin biosynthetic pathway genes and suppression of SQS in the qPCR analyses.


Artemisia annua L. Asteraceae Artemisinin Malaria and RNAi-technology 



Artemisinin-based combination therapies


Squalene synthase enzyme


Squalene synthase gene


6-Benzyle aminopurine




Gas chromatography–mass spectrometry


High performance liquid chromatography


Murashige and Skoog


Naphthalene acetic acid


National Institute Standard and Technology


Octopine synthase gene


Shoot-induction medium


Shoot-induction selection medium


Neomycin phosphatransferase gene



Authors are thankful to University Grants Commission (UGC), Government of India, for financial support to Department of Biotechnology under the scheme of UGC-SAP (DRS-1) to develop research advanced facilities used in this study. A. Ali and Khan S are thankful to UGC for providing Research Fellowship under UGC-SAP (BSR) scheme. The pHANNIBAL RNAi vector was gifted by CSIRO Plant Industry, PO Box 1600 Canberra ACT 2601, Australia. Technical help provided by Dr. Ajay Kumar, AIRF, School of Physical Sciences, JNU, New Delhi, India, for squalene analysis is greatly acknowledged.

Author contributions

MZA and AA developed the idea and critically editing the MS. AA conducted the experiments, wrote/finalized the MS. MMA helped in writing and data analysis. MAK helped in writing MS and interpretations of data. SK helped in experiments, writing and data analysis. All authors read and approved the final manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that he/she have no conflict of interest.


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Copyright information

© Accademia Nazionale dei Lincei 2017

Authors and Affiliations

  • Athar Ali
    • 1
  • Malik Mobeen Ahmad
    • 2
  • Mather Ali Khan
    • 3
  • Parul Saxena
    • 1
  • Shazia Khan
    • 1
  • Malik Zainul Abdin
    • 1
  1. 1.Center for Transgenic Plant Development, Department of Biotechnology, School of Chemical and Life SciencesHamdard UniversityNew DelhiIndia
  2. 2.Integral Institute of Agricultural Science and Technology (IIAST)Integral UniversityLucknowIndia
  3. 3.247 Bond Life Sciences CenterUniversity of MissouriColumbiaUSA

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