XVI International Botanical Congess

Lamiaceae are characterised by the presence of different types of glandular trichomes, which produce essential oils. According to ultrastructural studies, it seems that peltate trichomes contain the bulk of the essential oil production. Studies on terpenoid biosynthesis require the use of preparations containing adequate quantities of purified glandular trichomes. In this study we compare the metabolic activity of two distinct types of trichomes present on Leonotis leonurus leaves. Glandular trichomes were isolated and recovered without contamination of non-glandular hairs. Light microscopy revealed that trichomes are released from the epidermal surface by the stalk and have a normal appearance, seeming to be intact. Viability tests performed by vital staining and measurements of respiratory rates show the morphological and physiological integrity of the trichomes. Assays with [14C]IPP demonstrate their biosynthetic capacity to produce labelled terpenoids.