Influence of plant growth regulators on the growth and essential oil content of cultured Lavandula dentata plantlets

Micropropagation of L. dentata L. through shoot-tips (ca. 5 mm) was achieved successfully. Micropropagated plantlets were cultured without plant regulators in the culture medium (control) or in media containing 0.1 mg l⁻¹ of 6-benzyladenine (BA) and/or indole-3-butyric acid (IBA). These plantlets were examined for their essential oil content and composition in relation to growth rate and density and secretory or postsecretory stage of glandular hairs at five weeks of culture. The growth rates of these plantlets were not always correlated with their essential oil content (0.26%–0.65% v/w). However, all cultured plantlets showed a positive correlation between oil accumulation and the percentage of glandular hairs in secretory stage. Quantitative changes in the major monoterpene components (1,8-cineole, fenchol, borneol and camphor) and sesquiterpene content of plantlet oil, were also observed in response to the effect of varying growth regulator concentration in the culture medium. The influence of this effect on HMG-CoA reductase activity of cultured plantlets is also discussed. This revised version was published online in June 2006 with corrections to the Cover Date.