Industrial Crops and Products 34 (2011) 1465–1473 Contents lists available at ScienceDirect Industrial Crops and Products journa l h o me page: www.elsevier.com/locate/indcrop Increases in leaf artemisinin concentration in Artemisia annua in response to the application of phosphorus and boron M.J. Davies a , C.J. Atkinson a,∗ , C. Burns b , R. Arroo b , J. Woolley b a East Malling Research, New Road, East Malling, Kent ME19 6BJ, United Kingdom b De Montfort University, Leicester LE1 9BH, United Kingdom a r t i c l e i n f o Article history: Received 23 February 2011 Received in revised form 3 May 2011 Accepted 4 May 2011 Available online 2 June 2011 Keywords: Artemisia annua Artemisinin Boron Malaria Phosphorus Plant nutrition a b s t r a c t Malaria resurgence particularly in the third world is considerable and exacerbated by the development of multi-drug resistances to chemicals such as chloroquinone. Drug therapies, as recommended by WHO include the use of antimalarial compounds derived from Artemisia annua L., i.e. artemisinin-based ther- apies. This work aims to determine how A. annua plant dry matter can be enhanced while maximising artemisinin concentration from understanding the plant’s mineral requirements for P and B. Experiments with differing of P, from 5 to 120 mg L -1 and B from 0.1 to 0.9 mg L -1 were undertaken. Mineral nutrients were supplied in irrigation water to potted plants and after a period of growth, dry matter production and leaf artemisinin concentration were determined. Increases in P application enhanced plant growth and total dry matter production. An optimal application rate, with respect to dry matter, was apparent around 30 mg P L -1 . Despite increases in P application having no influence on leaf artemisinin concen- tration, optimal yields of artemisinin, on a per plant basis, were again achieved at supply rate around 30–60 mg L -1 . Increasing B application rate had little influence on dry matter production despite increases in B leaf tissue concentration promoting the total amount of B per plant. Leaf artemisinin concentration significantly increased with B application rate up to 0.6 mg B L -1 . The higher artemisinin concentrations when multiplied by total leaf dry matter at the higher B application rates produced an increase in total artemisinin production per plant. There was however no further significant effect on leaf artemisinin concentration when B supply concentrations increased further (0.9 mg L -1 ). Artemisinin production var- ied between the two experiments to a greater extent than plant dry matter production and the reasons for this are discussed in relation to growing environments and their possible impacts on artemisinin biosynthesis. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Efforts to reduce malaria have focused on ways to kill the par- asite (drug therapies, i.e. alkaloids) and the mosquito (using DDT) with some successes (Caniato and Puricelli, 2003). However, resis- tance of the Plasmodium (particularly Plasmodium falciparum, but emerging suggestions of Plasmodium vivax resistance) to cheap and safe drug treatments (chloroquine) has led to its resurgence (Kindermans et al., 2007). Single drug treatment approaches are not now encouraged due to induced resistance (Greenwood et al., 2008), and are being replaced by artemisinin-based combina- tion therapies (ACT) particularly in multi-drug-resistant situations (WHO, 2000). The chemical artemisinin and its derivatives, derived from Artemisia annua L. (qinghao or sweet wormwood), originally a native of Asia, Artemisia now grows wild throughout Europe, North and South America and Australia (Kindermans et al., 2007; Ferreira, ∗ Corresponding author. Tel.: +44 1732843833; fax: +44 1732849067. E-mail address: chris.atkinson@emr.ac.uk (C.J. Atkinson). 2007; Greenwood et al., 2008), is naturally wind-pollinated and favours outcrossing over selfing (Ferreira et al., 1997). The principal active compound artemisinin or qinghaosu, a sesquiterpene lactone (Klayman, 1985) is synthesised predominantly within specialised glandular leaf trichomes along with other terpenoids, at low con- centrations (0.1–0.6% dry weight) (Teoh et al., 2006; Putalun et al., 2007; Covello et al., 2007; Towler and Weathers, 2007; Covello, 2008; Maes et al., 2011). Uses of plant-based artemisinin compounds are not without sig- nificant cost, particularly in the third-world where their need is greatest. These costs are in part linked to limitations in the qual- ity of current germplasm (low active concentrations <1%, w/w), the negative impacts of the growing climate, poor agronomy and weak efficacy of post-harvest extraction. Despite the low biomass productivity of A. annua (1.5–2 tonnes ha -1 ) and artemisinin con- centrations, production of artemisinin between 6 and 14 kg per hectare is possible (Kindermans et al., 2007). There are good reasons why we should endeavour to enhance the concentration and yield, per plant, of artemisinin, and there are a number of routes to achieve this. Our aim is to examine the 0926-6690/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.indcrop.2011.05.002